m4: Use -U and -D in cc_fortify

Not just -D. This is to test the same thing
that gets used.

diff --git a/m4/cc_fortify.m4 b/m4/cc_fortify.m4
index aefa9c521b3c4fc8b5f3c0d4487ed5209271981c..3b01ec97cd5e51de9d837badab1456bdea130ee5 100644 (file)
--- a/m4/cc_fortify.m4
+++ b/m4/cc_fortify.m4
@@ -7,7 +7,7 @@ AC_DEFUN([AC_CC_D_FORTIFY_SOURCE],[
     if test $enable_hardening = yes; then
       case "$host" in
         *)
-          gl_COMPILER_OPTION_IF([-O2 -D_FORTIFY_SOURCE=2], [
+          gl_COMPILER_OPTION_IF([-O2 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2], [
             CFLAGS="$CFLAGS -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2"
             ],
             [],