Remove last dependency on the GdkPixbuf API

In test-pixmap.c instead of using the GdkPixbuf API to load the
redhand.png image we now use the cairo API to load the png into a xlib
surface which wraps our Pixmap.

This test was the last thing that depended on the gdk API and since
it's more concise to use Cairo here which is a hard dependency for
Clutter this change means we avoid depending on GdkPixbuf directly.

clutter/clutter-script.c

@@ -191,10 +191,6 @@
 #include <glib-object.h>
 #include <gmodule.h>
 
-#ifdef USE_GDKPIXBUF
-#include <gdk-pixbuf/gdk-pixbuf.h>
-#endif
-
 #include "clutter-actor.h"
 #include "clutter-alpha.h"
 #include "clutter-behaviour.h"