Removes Cogl from the repository

Cogl has now been split out into a standalone project with a separate
repository at git://git.gnome.org/cogl. From now on the Clutter build
will now simply look for a cogl-1.0 pkg-config file to find a suitable
Cogl library to link against at build time.

tests/interactive/test-box-layout.c

@@ -23,7 +23,7 @@
 
 #include <clutter/clutter.h>
 #include <cogl/cogl.h>
-#include "pango/cogl-pango.h"
+#include <cogl/cogl-pango.h>
 
 #define INSTRUCTIONS \
         "Press v\t\342\236\236\tSwitch horizontal/vertical\n"           \