Add transient parent and offset to QWaylandSurface

Compositors now know more about transient surfaces.
With the parent and offset information, compositors can place transient
surfaces relative to their parent.
Add a dummy cmake test. Fix build breakage

Change-Id: Id6e2d46b55e521218a3c0f44cf9a4a2be5f0df7f
Give a name to the event handling thread

Change-Id: I5c6073bc1908e54bc5ae50d4b6b6044974f1ad60