simple-egl: Add option -o to make surface opaque
simple-egl: Add option -o to make surface opaque

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