weston-test-client-helper: Use a frame callback to flush surface geometry
weston-test-client-helper: Use a frame callback to flush surface geometry

When moving a test surface, use a frame callback to make sure the
surface has been moved and the geometry updated.  The compositor may
delay updating the transform matrices, but once we get the frame
callback we know the surface has been repainted and the geometry
updated.

krezovic/weston,sir-murray/weston,Fantu/compositor-spice,mchalupa/weston,eyolfson/weston,Gnurou/weston,Fantu/compositor-spice,udoprog/weston,Tarnyko/weston-xdg_surface_present,Gnurou/weston,kwm81/weston,Fantu/compositor-spice,krezovic/weston,xorgy/weston,jonnylamb/weston,mchalupa/weston,Tarnyko/weston-xdg_surface_present,eyolfson/weston,udoprog/weston,jonnylamb/weston,kwm81/weston,giucam/weston,sir-murray/weston,giucam/weston,xorgy/weston