As observed in #420 (Running Weston under Weston's kiosk shell with
multiple outputs causes the scrollback to go nuts), not
being able to cope with (a correct) resize of the parent surface would
cause the client weston instance to spin forever. If dispatching
failed, just exit.
Fixes#420
Signed-off-by: Marius Vlad <marius.vlad@collabora.com>