Add X_CFLAGS to CPPFLAGS so that the X11 include path is used when looking for headers and testing for features.

Add defines needed for mingw32 build.

configure.in

@@ -314,6 +314,11 @@ AC_PROG_MAKE_SET
 
 AC_PATH_XTRA
 
+dnl Check in X11 include directory too.
+if test "$no_x" != "yes"; then
+    CPPFLAGS="$CPPFLAGS $X_CFLAGS"
+fi
+
 dnl ========================================================
 dnl set the defaults first
 dnl ========================================================
@@ -609,6 +614,10 @@ case "$target" in
 
 *-mingw*)
     AC_DEFINE(_WINDOWS)
+    AC_DEFINE(WIN32_LEAN_AND_MEAN)
+    AC_DEFINE(NONAMELESSUNION)
+    CFLAGS="$(CFLAGS) -fvtable-thunks"
+    CXXFLAGS="$(CXXFLAGS) -fvtable-thunks"
     TARGET_MD_ARCH=win32
     if test -z "$GNU_CC"; then
 	OBJ_SUFFIX=obj