patch 7.4.1437
Problem:    Old system doesn't have isinf() and NAN. (Ben Fritz)
Solution:   Adjust #ifdefs.  Detect isnan() and isinf() functions with
            configure. Use a replacement when missing. (Kazunobu Kuriyama)
diff --git a/src/auto/configure b/src/auto/configure
index 861fe4d..08af402 100755
--- a/src/auto/configure
+++ b/src/auto/configure
@@ -10978,6 +10978,48 @@
  presetting ac_cv_c_bigendian=no (or yes) will help" "$LINENO" 5 ;;
  esac
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for inline" >&5
+$as_echo_n "checking for inline... " >&6; }
+if ${ac_cv_c_inline+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_cv_c_inline=no
+for ac_kw in inline __inline__ __inline; do
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#ifndef __cplusplus
+typedef int foo_t;
+static $ac_kw foo_t static_foo () {return 0; }
+$ac_kw foo_t foo () {return 0; }
+#endif
+
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  ac_cv_c_inline=$ac_kw
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+  test "$ac_cv_c_inline" != no && break
+done
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_c_inline" >&5
+$as_echo "$ac_cv_c_inline" >&6; }
+
+case $ac_cv_c_inline in
+  inline | yes) ;;
+  *)
+    case $ac_cv_c_inline in
+      no) ac_val=;;
+      *) ac_val=$ac_cv_c_inline;;
+    esac
+    cat >>confdefs.h <<_ACEOF
+#ifndef __cplusplus
+#define inline $ac_val
+#endif
+_ACEOF
+    ;;
+esac
+
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for rlim_t" >&5
 $as_echo_n "checking for rlim_t... " >&6; }
@@ -11816,7 +11858,7 @@
 	setpgid setsid sigaltstack sigstack sigset sigsetjmp sigaction \
 	sigvec strcasecmp strerror strftime stricmp strncasecmp \
 	strnicmp strpbrk strtol tgetent towlower towupper iswupper \
-	usleep utime utimes
+	usleep utime utimes isnan isinf
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"