Flush the wayland events on the dispatcher's awake signal

This is not normally needed, but it is when an app, like our client test,
needs to have the requests flushed out by a QCoreApplication::processEvents
call.

Change-Id: Id821eaf5b612dc44281141181a09718f409e7eb6
Reviewed-by: Robin Burchell <robin.burchell@viroteck.net>
Fix client tests

Change-Id: I6511dfb826c522db3d8bd01c5670c06f187abff2
Reviewed-by: Robin Burchell <robin.burchell@viroteck.net>