waylandsink: Wait for the surface to be configured
With latest XDG shell, we need to fait for the surface to have been configured before we can attach a buffer to it. This is being enforce by Weston with an error.
Note that this now blocks on the compositor reply, which may never arrive. I believe we need to hook this up to the change state so that we can cancel the wait whenever the pipeline is cancelled.
Fixes #933 (closed)
Edited by Nicolas Dufresne