This makes sure the EGL_KHR_create_context enums are always defined in
cogl-winsys-egl.c so we will build with drivers that don't support this
extension. Cogl will do runtime checks to explicitly check that the
extension is available before ever referencing these enums so this is
safe to do.
https://bugzilla.gnome.org/show_bug.cgi?id=694537
Reviewed-by: Neil Roberts <neil@linux.intel.com>
(cherry picked from commit bd034b7451e7d9c602bcc91f1a00f6aaa7b05ec0)