xwayland: Add xdg-output v3 support
xdg-output v3 marks xdg-output.done as deprecated and compositors are not required to send that event anymore.
So if the xdg-output version is 3 or higher, simply set the initial
value xdg_output_done
to TRUE so we don't wait/expect that event
from the compositor.
Signed-off-by: Olivier Fourdan ofourdan@redhat.com