It looks like Cogl doesn't currently clean up an unallocated atlas
texture properly so if it fails to allocate it. It will then crash
when it is freed. This adds a conformance test to verify that all of
the various texture types can be freed without allocating them.
Reviewed-by: Robert Bragg <robert@linux.intel.com>
(cherry picked from commit bfada22d9a7f60baad5ae5615e45f10327e23e36)
