Previously CoglPipelineSnippetList was using the BSD embedded list
type with a mini struct to combine the list node with a pointer to the
snippet. This is effectively equivalent to just using a GList so we
might as well do that. This will help if we eventually want to get rid
of cogl-queue.h
Reviewed-by: Robert Bragg <robert@linux.intel.com>
(cherry picked from commit 54a168f3c7829c427d54ab517533bb9f7384d022)
ed510dbe6d