Workaround for MinGW non-standard strtod.

MinGW has reverted to using the Microsoft msvcrt0 implementation
of the strtod() function. This implementation doesn't accept "INF"
"NaN". MinGW does provide a C99 compliant implementation of this
function called __strtod(). We need to force the linker to replace
all references to strtod() with references to __strtod().

aclocal.m4

@@ -64,7 +64,7 @@ fi
 # AX_WIN32
 # --------
 # Combined check for several flavors of Microsoft Windows so
-# their "issues" can be dealt with
+ # their "issues" can be dealt with
 AC_DEFUN([AX_WIN32],
 [AC_MSG_CHECKING([for Microsoft Windows])
 AC_REQUIRE([AC_CANONICAL_HOST]) []dnl
@@ -230,6 +230,17 @@ case "${host}" in
 esac
 ])# AX_CPP_PRECOMP
 
+# AX_C99_STRTOD
+# -------------
+AC_DEFUN([AX_C99_STRTOD],
+[# On MinGW we need to jump through hoops to get a C99 compliant strtod().
+case "${host}" in
+    *-*-mingw*)
+        LDFLAGS="-Wl,--undefined=___strtod,--wrap,strtod,--defsym,___wrap_strtod=___strtod"
+        ;;
+esac
+])# AX_C99_STRTOD
+
 # When config.status generates a header, we must update the stamp-h file.
 # This file resides in the same directory as the config header
 # that is generated.  The stamp file name are based on the header name.

configure.in

@@ -192,6 +192,9 @@ AX_C_PICFLAG
 # may modify CPPFLAGS and CFLAGS
 AX_CPP_PRECOMP
 
+# may modify LDFLAGS
+AX_C99_STRTOD
+
 # Processor specific compile flags
 case "${host}" in
     alpha*-*-linux*)