This backports some changes to #319 to fix the screenshooter data
format. This also adds wlr_backend_get_renderer which will be
useful to support multiple renderers.
Add a signal for wlr_surface destruction on the wlr_surface that compositors
can listen to to remove the surface from their state.
Implement a listener for this in the example wl_compositor to remove the
surface from its internal list of surfaces.
Destroy the surface in the compositor destroy_surface callback given when the
surface resource was created.
Add a reference to the surface resource to the wlr_surface so a compositor can
find it in its list of resources upon wlr_resource destruction.
emersion
Scott Anderson
Dominique Martinet
Drew DeVault
nyorain
Tony Crisci