Revert "Acutally use GD_CFLAGS"

Maybe was irrelevant

This reverts commit 9dc6672.

Author: Girgias

ext/gd/config.m4

@@ -187,7 +187,7 @@ dnl Various checks for GD features
     AC_DEFINE(HAVE_LIBGD, 1, [ ])
     PHP_GD_CHECK_VERSION
 
-    PHP_NEW_EXTENSION(gd, gd.c $extra_sources, $ext_shared, , $GD_CFLAGS)
+    PHP_NEW_EXTENSION(gd, gd.c $extra_sources, $ext_shared)
     GD_HEADER_DIRS="ext/gd/"
     PHP_CHECK_LIBRARY(gd, gdImageCreate, [], [
       AC_MSG_ERROR([GD build test failed. Please check the config.log for details.])