XWayland expects the wl_output and xdg_output done calls always to come
in pairs. But when the wl_output position is not changed our
KWayland::Server::OutputInterface does not send a done event.
Then the next time a pair is sent before the xdg-output information is
received XWayland pairs the wl_output data with the data from the previous
xdg_output data, what breaks XWayland screen bound calculations and by that
This preliminary fix makes sure the events are only sent in pairs. Long-term
it would be nicer to have the synchronization directly in KWayland, such that
we don't need to check its expected behavior from the outside.