libgomp does not respect --disable-werror

https://bugs.gentoo.org/229059
http://gcc.gnu.org/PR38436


--- a/libgomp/configure
+++ b/libgomp/configure
@@ -4282,7 +4282,7 @@ save_CFLAGS="$CFLAGS"
 
 # Add -Wall -Werror if we are using GCC.
 if test "x$GCC" = "xyes"; then
-  XCFLAGS="$XCFLAGS -Wall -Werror"
+  XCFLAGS="$XCFLAGS -Wall"
 fi
 
 # Find other programs we need.