Allowing to use a simple event-like sync for the message queues.
-- v3: server: Use an internal event sync for message queues. server: Remove mostly unnecessary thread own queue check. server: Continuously poll on queue fd for driver events. win32u: Notify wineserver after processing every driver events. win32u: Return TRUE from ProcessEvents after emptying the event queue. win32u: Check for pending hardware messages after processing events. server: Use a dedicated internal bit for queued hardware messages.