Some of the Clutter code was using GL types for the primitive types
such as GLint and GLubyte and then passing these to Cogl. This doesn't
make much sense because the Cogl functions directly take native C
types. This patch just replaces them with either a native C type or a
glib type.

Some of the cogl conformance tests are trying to directly call GL for
example to test creating a foreign texture. These tests have been
changed to manually define the GL enum values instead of relying on a
GL header to define them.

This is necessary because Cogl may soon stop including a GL header
from its public headers.

Reviewed-by: Emmanuele Bassi <ebassi@linux.intel.com>