patch 8.1.1529: libcanberra is linked with even when not used

Problem:    Libcanberra is linked with even when not used.
Solution:   Have configure check for libcanberra only when wanted.
            (suggestions by Libor Bukata)
diff --git a/src/auto/configure b/src/auto/configure
index d5b4f60..c326abf 100755
--- a/src/auto/configure
+++ b/src/auto/configure
@@ -840,6 +840,7 @@
 with_motif_lib
 with_tlib
 enable_largefile
+enable_canberra
 enable_acl
 enable_gpm
 enable_sysmouse
@@ -1515,6 +1516,7 @@
   --disable-icon-cache-update        update disabled
   --disable-desktop-database-update  update disabled
   --disable-largefile     omit support for large files
+  --disable-canberra      Do not use libcanberra.
   --disable-acl           No check for ACL support.
   --disable-gpm           Don't use gpm (Linux mouse daemon).
   --disable-sysmouse      Don't use sysmouse (mouse in *BSD console).
@@ -12925,40 +12927,56 @@
 fi
 
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking --enable-canberra argument" >&5
+$as_echo_n "checking --enable-canberra argument... " >&6; }
+# Check whether --enable-canberra was given.
+if test "${enable_canberra+set}" = set; then :
+  enableval=$enable_canberra;
+else
+  enable_canberra="maybe"
+fi
 
-if test "x$PKG_CONFIG" != "xno"; then
-  canberra_lib=`$PKG_CONFIG --libs libcanberrax 2>/dev/null`
-  canberra_cflags=`$PKG_CONFIG --cflags libcanberrax 2>/dev/null`
-     { $as_echo "$as_me:${as_lineno-$LINENO}: result: canberra_lib: $canberra_lib" >&5
-$as_echo "canberra_lib: $canberra_lib" >&6; }
-     { $as_echo "$as_me:${as_lineno-$LINENO}: result: canberra_cflags: $canberra_cflags" >&5
-$as_echo "canberra_cflags: $canberra_cflags" >&6; }
+
+if test "$enable_canberra" = "maybe"; then
+  if test "$features" = "big" -o "$features" = "huge"; then
+    { $as_echo "$as_me:${as_lineno-$LINENO}: result: Defaulting to yes" >&5
+$as_echo "Defaulting to yes" >&6; }
+    enable_canberra="yes"
+  else
+    { $as_echo "$as_me:${as_lineno-$LINENO}: result: Defaulting to no" >&5
+$as_echo "Defaulting to no" >&6; }
+    enable_canberra="no"
+  fi
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $enable_canberra" >&5
+$as_echo "$enable_canberra" >&6; }
 fi
-if test "x$canberra_lib" = "x"; then
-  canberra_lib=-lcanberra
-  canberra_cflags=-D_REENTRANT
-fi
-     { $as_echo "$as_me:${as_lineno-$LINENO}: result: canberra_lib: $canberra_lib" >&5
-$as_echo "canberra_lib: $canberra_lib" >&6; }
-     { $as_echo "$as_me:${as_lineno-$LINENO}: result: canberra_cflags: $canberra_cflags" >&5
-$as_echo "canberra_cflags: $canberra_cflags" >&6; }
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for libcanberra" >&5
+if test "$enable_canberra" = "yes"; then
+  if test "x$PKG_CONFIG" != "xno"; then
+    canberra_lib=`$PKG_CONFIG --libs libcanberra 2>/dev/null`
+    canberra_cflags=`$PKG_CONFIG --cflags libcanberra 2>/dev/null`
+  fi
+  if test "x$canberra_lib" = "x"; then
+    canberra_lib=-lcanberra
+    canberra_cflags=-D_REENTRANT
+  fi
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for libcanberra" >&5
 $as_echo_n "checking for libcanberra... " >&6; }
-ac_save_CFLAGS="$CFLAGS"
-ac_save_LIBS="$LIBS"
-CFLAGS="$CFLAGS $canberra_cflags"
-LIBS="$LIBS $canberra_lib"
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+  ac_save_CFLAGS="$CFLAGS"
+  ac_save_LIBS="$LIBS"
+  CFLAGS="$CFLAGS $canberra_cflags"
+  LIBS="$LIBS $canberra_lib"
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
-# include <canberra.h>
+  # include <canberra.h>
 
 int
 main ()
 {
 
-   ca_context *hello;
-   ca_context_create(&hello);
+     ca_context *hello;
+     ca_context_create(&hello);
   ;
   return 0;
 }
@@ -12973,6 +12991,7 @@
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
+fi
 
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for st_blksize" >&5