Don't use config.h in clutter and cogl

In cogl use cogl-config.h and in clutter use clutter-build-config.h. We
can't use clutter-config.h in clutter because its already used and
installed.

https://bugzilla.gnome.org/show_bug.cgi?id=768976

clutter/clutter/clutter-util.c

@@ -31,7 +31,7 @@
  */
 
 #ifdef HAVE_CONFIG_H
-#include "config.h"
+#include "clutter-build-config.h"
 #endif
 
 #include <math.h>