Change unsigned int initialization from -1 to !0
Change unsigned int initialization from -1 to !0

Fixes compilation error "unary negation of unsigned integers may be
removed in the future"

bvssvni/gfx-rs,red75prime/gfx,JohnColanduoni/gfx,tanderegg/gfx,davll/gfx,ColinKinloch/gfx,ColinKinloch/gfx,aepsil0n/gfx-rs,tanderegg/gfx,alexcrichton/gfx,Bastacyclop/gfx,tempbottle/gfx,sectopod/gfx-rs,mitchmindtree/gfx-rs,JohnColanduoni/gfx,gfx-rs/gfx-rs