cogland: Handle damage events for non-shm buffers too
cogland: Handle damage events for non-shm buffers too

When a Wayland compositor gets a commit it only needs to redraw the
region specified by the pending damage event. Previously Cogland was
ignoring damage events for non-shm buffers and just always queuing a
redraw after a commit event. This patch changes it to queue a redraw
only in response to a damage event. In practice this doesn't really
make much difference because Cogland doesn't do anything clever to
handle updating a sub-region of the screen, but it more costly matches
the model a compositor should use.

Reviewed-by: Robert Bragg <12e9293ec6b30c7fa8a0926af42807e929c1684f@linux.intel.com>

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