xwayland: Clean up unpaired surfaces
xwayland: Clean up unpaired surfaces

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