diff --git a/unix/m4/lib-link.m4 b/unix/m4/lib-link.m4
new file mode 100644
index 0000000..ea0b0c4
--- /dev/null
+++ b/unix/m4/lib-link.m4
@@ -0,0 +1,553 @@
+# lib-link.m4 serial 6 (gettext-0.14.3)
+dnl Copyright (C) 2001-2005 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl From Bruno Haible.
+
+AC_PREREQ(2.50)
+
+dnl AC_LIB_LINKFLAGS(name [, dependencies]) searches for libname and
+dnl the libraries corresponding to explicit and implicit dependencies.
+dnl Sets and AC_SUBSTs the LIB${NAME} and LTLIB${NAME} variables and
+dnl augments the CPPFLAGS variable.
+AC_DEFUN([AC_LIB_LINKFLAGS],
+[
+  AC_REQUIRE([AC_LIB_PREPARE_PREFIX])
+  AC_REQUIRE([AC_LIB_RPATH])
+  define([Name],[translit([$1],[./-], [___])])
+  define([NAME],[translit([$1],[abcdefghijklmnopqrstuvwxyz./-],
+                               [ABCDEFGHIJKLMNOPQRSTUVWXYZ___])])
+  AC_CACHE_CHECK([how to link with lib[]$1], [ac_cv_lib[]Name[]_libs], [
+    AC_LIB_LINKFLAGS_BODY([$1], [$2])
+    ac_cv_lib[]Name[]_libs="$LIB[]NAME"
+    ac_cv_lib[]Name[]_ltlibs="$LTLIB[]NAME"
+    ac_cv_lib[]Name[]_cppflags="$INC[]NAME"
+  ])
+  LIB[]NAME="$ac_cv_lib[]Name[]_libs"
+  LTLIB[]NAME="$ac_cv_lib[]Name[]_ltlibs"
+  INC[]NAME="$ac_cv_lib[]Name[]_cppflags"
+  AC_LIB_APPENDTOVAR([CPPFLAGS], [$INC]NAME)
+  AC_SUBST([LIB]NAME)
+  AC_SUBST([LTLIB]NAME)
+  dnl Also set HAVE_LIB[]NAME so that AC_LIB_HAVE_LINKFLAGS can reuse the
+  dnl results of this search when this library appears as a dependency.
+  HAVE_LIB[]NAME=yes
+  undefine([Name])
+  undefine([NAME])
+])
+
+dnl AC_LIB_HAVE_LINKFLAGS(name, dependencies, includes, testcode)
+dnl searches for libname and the libraries corresponding to explicit and
+dnl implicit dependencies, together with the specified include files and
+dnl the ability to compile and link the specified testcode. If found, it
+dnl sets and AC_SUBSTs HAVE_LIB${NAME}=yes and the LIB${NAME} and
+dnl LTLIB${NAME} variables and augments the CPPFLAGS variable, and
+dnl #defines HAVE_LIB${NAME} to 1. Otherwise, it sets and AC_SUBSTs
+dnl HAVE_LIB${NAME}=no and LIB${NAME} and LTLIB${NAME} to empty.
+AC_DEFUN([AC_LIB_HAVE_LINKFLAGS],
+[
+  AC_REQUIRE([AC_LIB_PREPARE_PREFIX])
+  AC_REQUIRE([AC_LIB_RPATH])
+  define([Name],[translit([$1],[./-], [___])])
+  define([NAME],[translit([$1],[abcdefghijklmnopqrstuvwxyz./-],
+                               [ABCDEFGHIJKLMNOPQRSTUVWXYZ___])])
+
+  dnl Search for lib[]Name and define LIB[]NAME, LTLIB[]NAME and INC[]NAME
+  dnl accordingly.
+  AC_LIB_LINKFLAGS_BODY([$1], [$2])
+
+  dnl Add $INC[]NAME to CPPFLAGS before performing the following checks,
+  dnl because if the user has installed lib[]Name and not disabled its use
+  dnl via --without-lib[]Name-prefix, he wants to use it.
+  ac_save_CPPFLAGS="$CPPFLAGS"
+  AC_LIB_APPENDTOVAR([CPPFLAGS], [$INC]NAME)
+
+  AC_CACHE_CHECK([for lib[]$1], [ac_cv_lib[]Name], [
+    ac_save_LIBS="$LIBS"
+    LIBS="$LIBS $LIB[]NAME"
+    AC_TRY_LINK([$3], [$4], [ac_cv_lib[]Name=yes], [ac_cv_lib[]Name=no])
+    LIBS="$ac_save_LIBS"
+  ])
+  if test "$ac_cv_lib[]Name" = yes; then
+    HAVE_LIB[]NAME=yes
+    AC_DEFINE([HAVE_LIB]NAME, 1, [Define if you have the $1 library.])
+    AC_MSG_CHECKING([how to link with lib[]$1])
+    AC_MSG_RESULT([$LIB[]NAME])
+  else
+    HAVE_LIB[]NAME=no
+    dnl If $LIB[]NAME didn't lead to a usable library, we don't need
+    dnl $INC[]NAME either.
+    CPPFLAGS="$ac_save_CPPFLAGS"
+    LIB[]NAME=
+    LTLIB[]NAME=
+  fi
+  AC_SUBST([HAVE_LIB]NAME)
+  AC_SUBST([LIB]NAME)
+  AC_SUBST([LTLIB]NAME)
+  undefine([Name])
+  undefine([NAME])
+])
+
+dnl Determine the platform dependent parameters needed to use rpath:
+dnl libext, shlibext, hardcode_libdir_flag_spec, hardcode_libdir_separator,
+dnl hardcode_direct, hardcode_minus_L.
+AC_DEFUN([AC_LIB_RPATH],
+[
+  dnl Tell automake >= 1.10 to complain if config.rpath is missing.
+  m4_ifdef([AC_REQUIRE_AUX_FILE], [AC_REQUIRE_AUX_FILE([config.rpath])])
+  AC_REQUIRE([AC_PROG_CC])                dnl we use $CC, $GCC, $LDFLAGS
+  AC_REQUIRE([AC_LIB_PROG_LD])            dnl we use $LD, $with_gnu_ld
+  AC_REQUIRE([AC_CANONICAL_HOST])         dnl we use $host
+  AC_REQUIRE([AC_CONFIG_AUX_DIR_DEFAULT]) dnl we use $ac_aux_dir
+  AC_CACHE_CHECK([for shared library run path origin], acl_cv_rpath, [
+    CC="$CC" GCC="$GCC" LDFLAGS="$LDFLAGS" LD="$LD" with_gnu_ld="$with_gnu_ld" \
+    ${CONFIG_SHELL-/bin/sh} "$ac_aux_dir/config.rpath" "$host" > conftest.sh
+    . ./conftest.sh
+    rm -f ./conftest.sh
+    acl_cv_rpath=done
+  ])
+  wl="$acl_cv_wl"
+  libext="$acl_cv_libext"
+  shlibext="$acl_cv_shlibext"
+  hardcode_libdir_flag_spec="$acl_cv_hardcode_libdir_flag_spec"
+  hardcode_libdir_separator="$acl_cv_hardcode_libdir_separator"
+  hardcode_direct="$acl_cv_hardcode_direct"
+  hardcode_minus_L="$acl_cv_hardcode_minus_L"
+  dnl Determine whether the user wants rpath handling at all.
+  AC_ARG_ENABLE(rpath,
+    [  --disable-rpath         do not hardcode runtime library paths],
+    :, enable_rpath=yes)
+])
+
+dnl AC_LIB_LINKFLAGS_BODY(name [, dependencies]) searches for libname and
+dnl the libraries corresponding to explicit and implicit dependencies.
+dnl Sets the LIB${NAME}, LTLIB${NAME} and INC${NAME} variables.
+AC_DEFUN([AC_LIB_LINKFLAGS_BODY],
+[
+  define([NAME],[translit([$1],[abcdefghijklmnopqrstuvwxyz./-],
+                               [ABCDEFGHIJKLMNOPQRSTUVWXYZ___])])
+  dnl By default, look in $includedir and $libdir.
+  use_additional=yes
+  AC_LIB_WITH_FINAL_PREFIX([
+    eval additional_includedir=\"$includedir\"
+    eval additional_libdir=\"$libdir\"
+  ])
+  AC_LIB_ARG_WITH([lib$1-prefix],
+[  --with-lib$1-prefix[=DIR]  search for lib$1 in DIR/include and DIR/lib
+  --without-lib$1-prefix     don't search for lib$1 in includedir and libdir],
+[
+    if test "X$withval" = "Xno"; then
+      use_additional=no
+    else
+      if test "X$withval" = "X"; then
+        AC_LIB_WITH_FINAL_PREFIX([
+          eval additional_includedir=\"$includedir\"
+          eval additional_libdir=\"$libdir\"
+        ])
+      else
+        additional_includedir="$withval/include"
+        additional_libdir="$withval/lib"
+      fi
+    fi
+])
+  dnl Search the library and its dependencies in $additional_libdir and
+  dnl $LDFLAGS. Using breadth-first-seach.
+  LIB[]NAME=
+  LTLIB[]NAME=
+  INC[]NAME=
+  rpathdirs=
+  ltrpathdirs=
+  names_already_handled=
+  names_next_round='$1 $2'
+  while test -n "$names_next_round"; do
+    names_this_round="$names_next_round"
+    names_next_round=
+    for name in $names_this_round; do
+      already_handled=
+      for n in $names_already_handled; do
+        if test "$n" = "$name"; then
+          already_handled=yes
+          break
+        fi
+      done
+      if test -z "$already_handled"; then
+        names_already_handled="$names_already_handled $name"
+        dnl See if it was already located by an earlier AC_LIB_LINKFLAGS
+        dnl or AC_LIB_HAVE_LINKFLAGS call.
+        uppername=`echo "$name" | sed -e 'y|abcdefghijklmnopqrstuvwxyz./-|ABCDEFGHIJKLMNOPQRSTUVWXYZ___|'`
+        eval value=\"\$HAVE_LIB$uppername\"
+        if test -n "$value"; then
+          if test "$value" = yes; then
+            eval value=\"\$LIB$uppername\"
+            test -z "$value" || LIB[]NAME="${LIB[]NAME}${LIB[]NAME:+ }$value"
+            eval value=\"\$LTLIB$uppername\"
+            test -z "$value" || LTLIB[]NAME="${LTLIB[]NAME}${LTLIB[]NAME:+ }$value"
+          else
+            dnl An earlier call to AC_LIB_HAVE_LINKFLAGS has determined
+            dnl that this library doesn't exist. So just drop it.
+            :
+          fi
+        else
+          dnl Search the library lib$name in $additional_libdir and $LDFLAGS
+          dnl and the already constructed $LIBNAME/$LTLIBNAME.
+          found_dir=
+          found_la=
+          found_so=
+          found_a=
+          if test $use_additional = yes; then
+            if test -n "$shlibext" && test -f "$additional_libdir/lib$name.$shlibext"; then
+              found_dir="$additional_libdir"
+              found_so="$additional_libdir/lib$name.$shlibext"
+              if test -f "$additional_libdir/lib$name.la"; then
+                found_la="$additional_libdir/lib$name.la"
+              fi
+            else
+              if test -f "$additional_libdir/lib$name.$libext"; then
+                found_dir="$additional_libdir"
+                found_a="$additional_libdir/lib$name.$libext"
+                if test -f "$additional_libdir/lib$name.la"; then
+                  found_la="$additional_libdir/lib$name.la"
+                fi
+              fi
+            fi
+          fi
+          if test "X$found_dir" = "X"; then
+            for x in $LDFLAGS $LTLIB[]NAME; do
+              AC_LIB_WITH_FINAL_PREFIX([eval x=\"$x\"])
+              case "$x" in
+                -L*)
+                  dir=`echo "X$x" | sed -e 's/^X-L//'`
+                  if test -n "$shlibext" && test -f "$dir/lib$name.$shlibext"; then
+                    found_dir="$dir"
+                    found_so="$dir/lib$name.$shlibext"
+                    if test -f "$dir/lib$name.la"; then
+                      found_la="$dir/lib$name.la"
+                    fi
+                  else
+                    if test -f "$dir/lib$name.$libext"; then
+                      found_dir="$dir"
+                      found_a="$dir/lib$name.$libext"
+                      if test -f "$dir/lib$name.la"; then
+                        found_la="$dir/lib$name.la"
+                      fi
+                    fi
+                  fi
+                  ;;
+              esac
+              if test "X$found_dir" != "X"; then
+                break
+              fi
+            done
+          fi
+          if test "X$found_dir" != "X"; then
+            dnl Found the library.
+            LTLIB[]NAME="${LTLIB[]NAME}${LTLIB[]NAME:+ }-L$found_dir -l$name"
+            if test "X$found_so" != "X"; then
+              dnl Linking with a shared library. We attempt to hardcode its
+              dnl directory into the executable's runpath, unless it's the
+              dnl standard /usr/lib.
+              if test "$enable_rpath" = no || test "X$found_dir" = "X/usr/lib"; then
+                dnl No hardcoding is needed.
+                LIB[]NAME="${LIB[]NAME}${LIB[]NAME:+ }$found_so"
+              else
+                dnl Use an explicit option to hardcode DIR into the resulting
+                dnl binary.
+                dnl Potentially add DIR to ltrpathdirs.
+                dnl The ltrpathdirs will be appended to $LTLIBNAME at the end.
+                haveit=
+                for x in $ltrpathdirs; do
+                  if test "X$x" = "X$found_dir"; then
+                    haveit=yes
+                    break
+                  fi
+                done
+                if test -z "$haveit"; then
+                  ltrpathdirs="$ltrpathdirs $found_dir"
+                fi
+                dnl The hardcoding into $LIBNAME is system dependent.
+                if test "$hardcode_direct" = yes; then
+                  dnl Using DIR/libNAME.so during linking hardcodes DIR into the
+                  dnl resulting binary.
+                  LIB[]NAME="${LIB[]NAME}${LIB[]NAME:+ }$found_so"
+                else
+                  if test -n "$hardcode_libdir_flag_spec" && test "$hardcode_minus_L" = no; then
+                    dnl Use an explicit option to hardcode DIR into the resulting
+                    dnl binary.
+                    LIB[]NAME="${LIB[]NAME}${LIB[]NAME:+ }$found_so"
+                    dnl Potentially add DIR to rpathdirs.
+                    dnl The rpathdirs will be appended to $LIBNAME at the end.
+                    haveit=
+                    for x in $rpathdirs; do
+                      if test "X$x" = "X$found_dir"; then
+                        haveit=yes
+                        break
+                      fi
+                    done
+                    if test -z "$haveit"; then
+                      rpathdirs="$rpathdirs $found_dir"
+                    fi
+                  else
+                    dnl Rely on "-L$found_dir".
+                    dnl But don't add it if it's already contained in the LDFLAGS
+                    dnl or the already constructed $LIBNAME
+                    haveit=
+                    for x in $LDFLAGS $LIB[]NAME; do
+                      AC_LIB_WITH_FINAL_PREFIX([eval x=\"$x\"])
+                      if test "X$x" = "X-L$found_dir"; then
+                        haveit=yes
+                        break
+                      fi
+                    done
+                    if test -z "$haveit"; then
+                      LIB[]NAME="${LIB[]NAME}${LIB[]NAME:+ }-L$found_dir"
+                    fi
+                    if test "$hardcode_minus_L" != no; then
+                      dnl FIXME: Not sure whether we should use
+                      dnl "-L$found_dir -l$name" or "-L$found_dir $found_so"
+                      dnl here.
+                      LIB[]NAME="${LIB[]NAME}${LIB[]NAME:+ }$found_so"
+                    else
+                      dnl We cannot use $hardcode_runpath_var and LD_RUN_PATH
+                      dnl here, because this doesn't fit in flags passed to the
+                      dnl compiler. So give up. No hardcoding. This affects only
+                      dnl very old systems.
+                      dnl FIXME: Not sure whether we should use
+                      dnl "-L$found_dir -l$name" or "-L$found_dir $found_so"
+                      dnl here.
+                      LIB[]NAME="${LIB[]NAME}${LIB[]NAME:+ }-l$name"
+                    fi
+                  fi
+                fi
+              fi
+            else
+              if test "X$found_a" != "X"; then
+                dnl Linking with a static library.
+                LIB[]NAME="${LIB[]NAME}${LIB[]NAME:+ }$found_a"
+              else
+                dnl We shouldn't come here, but anyway it's good to have a
+                dnl fallback.
+                LIB[]NAME="${LIB[]NAME}${LIB[]NAME:+ }-L$found_dir -l$name"
+              fi
+            fi
+            dnl Assume the include files are nearby.
+            additional_includedir=
+            case "$found_dir" in
+              */lib | */lib/)
+                basedir=`echo "X$found_dir" | sed -e 's,^X,,' -e 's,/lib/*$,,'`
+                additional_includedir="$basedir/include"
+                ;;
+            esac
+            if test "X$additional_includedir" != "X"; then
+              dnl Potentially add $additional_includedir to $INCNAME.
+              dnl But don't add it
+              dnl   1. if it's the standard /usr/include,
+              dnl   2. if it's /usr/local/include and we are using GCC on Linux,
+              dnl   3. if it's already present in $CPPFLAGS or the already
+              dnl      constructed $INCNAME,
+              dnl   4. if it doesn't exist as a directory.
+              if test "X$additional_includedir" != "X/usr/include"; then
+                haveit=
+                if test "X$additional_includedir" = "X/usr/local/include"; then
+                  if test -n "$GCC"; then
+                    case $host_os in
+                      linux* | gnu* | k*bsd*-gnu) haveit=yes;;
+                    esac
+                  fi
+                fi
+                if test -z "$haveit"; then
+                  for x in $CPPFLAGS $INC[]NAME; do
+                    AC_LIB_WITH_FINAL_PREFIX([eval x=\"$x\"])
+                    if test "X$x" = "X-I$additional_includedir"; then
+                      haveit=yes
+                      break
+                    fi
+                  done
+                  if test -z "$haveit"; then
+                    if test -d "$additional_includedir"; then
+                      dnl Really add $additional_includedir to $INCNAME.
+                      INC[]NAME="${INC[]NAME}${INC[]NAME:+ }-I$additional_includedir"
+                    fi
+                  fi
+                fi
+              fi
+            fi
+            dnl Look for dependencies.
+            if test -n "$found_la"; then
+              dnl Read the .la file. It defines the variables
+              dnl dlname, library_names, old_library, dependency_libs, current,
+              dnl age, revision, installed, dlopen, dlpreopen, libdir.
+              save_libdir="$libdir"
+              case "$found_la" in
+                */* | *\\*) . "$found_la" ;;
+                *) . "./$found_la" ;;
+              esac
+              libdir="$save_libdir"
+              dnl We use only dependency_libs.
+              for dep in $dependency_libs; do
+                case "$dep" in
+                  -L*)
+                    additional_libdir=`echo "X$dep" | sed -e 's/^X-L//'`
+                    dnl Potentially add $additional_libdir to $LIBNAME and $LTLIBNAME.
+                    dnl But don't add it
+                    dnl   1. if it's the standard /usr/lib,
+                    dnl   2. if it's /usr/local/lib and we are using GCC on Linux,
+                    dnl   3. if it's already present in $LDFLAGS or the already
+                    dnl      constructed $LIBNAME,
+                    dnl   4. if it doesn't exist as a directory.
+                    if test "X$additional_libdir" != "X/usr/lib"; then
+                      haveit=
+                      if test "X$additional_libdir" = "X/usr/local/lib"; then
+                        if test -n "$GCC"; then
+                          case $host_os in
+                            linux* | gnu* | k*bsd*-gnu) haveit=yes;;
+                          esac
+                        fi
+                      fi
+                      if test -z "$haveit"; then
+                        haveit=
+                        for x in $LDFLAGS $LIB[]NAME; do
+                          AC_LIB_WITH_FINAL_PREFIX([eval x=\"$x\"])
+                          if test "X$x" = "X-L$additional_libdir"; then
+                            haveit=yes
+                            break
+                          fi
+                        done
+                        if test -z "$haveit"; then
+                          if test -d "$additional_libdir"; then
+                            dnl Really add $additional_libdir to $LIBNAME.
+                            LIB[]NAME="${LIB[]NAME}${LIB[]NAME:+ }-L$additional_libdir"
+                          fi
+                        fi
+                        haveit=
+                        for x in $LDFLAGS $LTLIB[]NAME; do
+                          AC_LIB_WITH_FINAL_PREFIX([eval x=\"$x\"])
+                          if test "X$x" = "X-L$additional_libdir"; then
+                            haveit=yes
+                            break
+                          fi
+                        done
+                        if test -z "$haveit"; then
+                          if test -d "$additional_libdir"; then
+                            dnl Really add $additional_libdir to $LTLIBNAME.
+                            LTLIB[]NAME="${LTLIB[]NAME}${LTLIB[]NAME:+ }-L$additional_libdir"
+                          fi
+                        fi
+                      fi
+                    fi
+                    ;;
+                  -R*)
+                    dir=`echo "X$dep" | sed -e 's/^X-R//'`
+                    if test "$enable_rpath" != no; then
+                      dnl Potentially add DIR to rpathdirs.
+                      dnl The rpathdirs will be appended to $LIBNAME at the end.
+                      haveit=
+                      for x in $rpathdirs; do
+                        if test "X$x" = "X$dir"; then
+                          haveit=yes
+                          break
+                        fi
+                      done
+                      if test -z "$haveit"; then
+                        rpathdirs="$rpathdirs $dir"
+                      fi
+                      dnl Potentially add DIR to ltrpathdirs.
+                      dnl The ltrpathdirs will be appended to $LTLIBNAME at the end.
+                      haveit=
+                      for x in $ltrpathdirs; do
+                        if test "X$x" = "X$dir"; then
+                          haveit=yes
+                          break
+                        fi
+                      done
+                      if test -z "$haveit"; then
+                        ltrpathdirs="$ltrpathdirs $dir"
+                      fi
+                    fi
+                    ;;
+                  -l*)
+                    dnl Handle this in the next round.
+                    names_next_round="$names_next_round "`echo "X$dep" | sed -e 's/^X-l//'`
+                    ;;
+                  *.la)
+                    dnl Handle this in the next round. Throw away the .la's
+                    dnl directory; it is already contained in a preceding -L
+                    dnl option.
+                    names_next_round="$names_next_round "`echo "X$dep" | sed -e 's,^X.*/,,' -e 's,^lib,,' -e 's,\.la$,,'`
+                    ;;
+                  *)
+                    dnl Most likely an immediate library name.
+                    LIB[]NAME="${LIB[]NAME}${LIB[]NAME:+ }$dep"
+                    LTLIB[]NAME="${LTLIB[]NAME}${LTLIB[]NAME:+ }$dep"
+                    ;;
+                esac
+              done
+            fi
+          else
+            dnl Didn't find the library; assume it is in the system directories
+            dnl known to the linker and runtime loader. (All the system
+            dnl directories known to the linker should also be known to the
+            dnl runtime loader, otherwise the system is severely misconfigured.)
+            LIB[]NAME="${LIB[]NAME}${LIB[]NAME:+ }-l$name"
+            LTLIB[]NAME="${LTLIB[]NAME}${LTLIB[]NAME:+ }-l$name"
+          fi
+        fi
+      fi
+    done
+  done
+  if test "X$rpathdirs" != "X"; then
+    if test -n "$hardcode_libdir_separator"; then
+      dnl Weird platform: only the last -rpath option counts, the user must
+      dnl pass all path elements in one option. We can arrange that for a
+      dnl single library, but not when more than one $LIBNAMEs are used.
+      alldirs=
+      for found_dir in $rpathdirs; do
+        alldirs="${alldirs}${alldirs:+$hardcode_libdir_separator}$found_dir"
+      done
+      dnl Note: hardcode_libdir_flag_spec uses $libdir and $wl.
+      acl_save_libdir="$libdir"
+      libdir="$alldirs"
+      eval flag=\"$hardcode_libdir_flag_spec\"
+      libdir="$acl_save_libdir"
+      LIB[]NAME="${LIB[]NAME}${LIB[]NAME:+ }$flag"
+    else
+      dnl The -rpath options are cumulative.
+      for found_dir in $rpathdirs; do
+        acl_save_libdir="$libdir"
+        libdir="$found_dir"
+        eval flag=\"$hardcode_libdir_flag_spec\"
+        libdir="$acl_save_libdir"
+        LIB[]NAME="${LIB[]NAME}${LIB[]NAME:+ }$flag"
+      done
+    fi
+  fi
+  if test "X$ltrpathdirs" != "X"; then
+    dnl When using libtool, the option that works for both libraries and
+    dnl executables is -R. The -R options are cumulative.
+    for found_dir in $ltrpathdirs; do
+      LTLIB[]NAME="${LTLIB[]NAME}${LTLIB[]NAME:+ }-R$found_dir"
+    done
+  fi
+])
+
+dnl AC_LIB_APPENDTOVAR(VAR, CONTENTS) appends the elements of CONTENTS to VAR,
+dnl unless already present in VAR.
+dnl Works only for CPPFLAGS, not for LIB* variables because that sometimes
+dnl contains two or three consecutive elements that belong together.
+AC_DEFUN([AC_LIB_APPENDTOVAR],
+[
+  for element in [$2]; do
+    haveit=
+    for x in $[$1]; do
+      AC_LIB_WITH_FINAL_PREFIX([eval x=\"$x\"])
+      if test "X$x" = "X$element"; then
+        haveit=yes
+        break
+      fi
+    done
+    if test -z "$haveit"; then
+      [$1]="${[$1]}${[$1]:+ }$element"
+    fi
+  done
+])