cairo-util: Kill a duplicate test
cairo-util: Kill a duplicate test

If !(x < margin), then clearly margin <= x. No need to test for it again.

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