Previously if a client sent a commit message without attaching a new
buffer then it would end up detaching the existing buffer because
surface->pending.buffer would be NULL. This patch makes it explicitly
track when an attach is sent for a commit and so that it can avoid
making any changes otherwise. This fixes cases where GTK apps would
send a damage event without a new buffer.
Reviewed-by: Robert Bragg <robert@linux.intel.com>
(cherry picked from commit aa412b9c709120bd8d88a014010c448f3b9fcfb7)
32a0f88b04
