wayland: respond to ping requests from the compositor
wayland: respond to ping requests from the compositor

The ping/pong protocol on the shell surface is used by the compositor to
check that the client is responding to requests. This change adds a
listener for the shell surface and implements the ping handler to
respond to the requests from the compositor.

As the wayland dispatch infrastructure does not support having NULL
values for the members of the listener it is necessary to provide empty
implementations for the other events that the listener handles.

Signed-off-by: Rob Bradford <7e09c9d3e96378bf549fc283fd6e1e5b7014cc33@linux.intel.com>
Signed-off-by: Chad Versace <a557f7f75bf28dc19ac99107f5cc7cd6b3fbdb1a@linux.intel.com>

chadversary/waffle,fjhenigman/waffle,yinquan529/waffle-gl-waffle,dcbaker/waffle,evelikov/waffle,chadversary/waffle,evelikov/waffle,maurossi/waffle,yinquan529/waffle-gl-waffle,maurossi/waffle,waffle-gl/waffle,fjhenigman/waffle,waffle-gl/waffle,janesma/waffle,dcbaker/waffle,yinquan529/waffle-gl-waffle,chadversary/waffle,evelikov/waffle,fjhenigman/waffle,dcbaker/waffle,waffle-gl/waffle,janesma/waffle,maurossi/waffle,janesma/waffle,waffle-gl/waffle