Enable -Werror for all of qtxmlpatterns

Change-Id: Ic385a3589c3c84fdd7e0c73f69ac319d0543009c
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>
Merge remote-tracking branch 'origin/stable' into dev

Change-Id: I918b255b204a5246fa9cdc9ed3f8c7d71ab01e35