compositor: Do not leak old client buffers
compositor: Do not leak old client buffers

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