screenshooter: Don't assume output offsets start at zero
screenshooter: Don't assume output offsets start at zero

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