This adds some utility code to help us manage lists of closures
consistently within Cogl. The utilities are from Rig and were originally
written by Neil Roberts.
This adapts the way we track CoglOnscreen resize and frame closures to
use the new utilities.
Reviewed-by: Neil Roberts <neil@linux.intel.com>
(cherry picked from commit 2e15fc76eb29bf5932418f7ee80f1fcb2f6a816c)
