window: Only set opaque and input regions if they change
window: Only set opaque and input regions if they change

Setting these regions damages the entire window or causes a repick, which
we don't want to trigger if we don't need to.

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