clutter-stage-wayland: Enable clipped redraws
clutter-stage-wayland: Enable clipped redraws

_clutter_stage_window_can_clip_redraws is used to check for clipped redraws
support but can_clip_redraws is not implemented by clutter-stage-wayland so
it always returns FALSE causing full screen redraws.

Fix that by implementing can_clip_redraws in clutter-stage-wayland.

https://bugzilla.gnome.org/show_bug.cgi?id=726315

djdeath/clutter,GNOME/clutter,jigpu/clutter,jigpu/clutter,djdeath/clutter,jigpu/clutter,Distrotech/clutter,djdeath/clutter,Distrotech/clutter,ebassi/clutter,Distrotech/clutter,ebassi/clutter,djdeath/clutter,djdeath/clutter,ebassi/clutter,GNOME/clutter,ebassi/clutter,djdeath/clutter,GNOME/clutter,jigpu/clutter,GNOME/clutter,Distrotech/clutter,jigpu/clutter,Distrotech/clutter,jigpu/clutter,GNOME/clutter,ebassi/clutter,Distrotech/clutter