cogl-winsys-glx: Fix the comparison in find_onscreen_for_xid
cogl-winsys-glx: Fix the comparison in find_onscreen_for_xid

The comparison for finding onscreen framebuffers in
find_onscreen_for_xid had a small thinko so that it would ignore
framebuffers when the negation of the type is onscreen. This ends up
doing the right thing anyway because the onscreen type has the value 0
and the offscreen type has the value 1 but presumably it would fail if
we ever added any other framebuffer types.

heysion/clutter-clone,ebassi/clutter,djdeath/clutter,collects/clutter,GNOME/clutter,djdeath/clutter,ebassi/clutter,collects/clutter,ebassi/clutter,Distrotech/clutter,spatulasnout/clutter,GNOME/clutter,Distrotech/clutter,Distrotech/clutter,ebassi/clutter,jigpu/clutter,djdeath/clutter-multithreaded,Distrotech/clutter,djdeath/clutter,Distrotech/clutter,dlespiau/clutter,kerrickstaley/clutter-vala,spatulasnout/clutter,kerrickstaley/clutter-vala,GNOME/clutter,djdeath/clutter,jigpu/clutter,GNOME/clutter,dlespiau/clutter,heysion/clutter-clone,djdeath/clutter-multithreaded,spatulasnout/clutter,jigpu/clutter,djdeath/clutter,ebassi/clutter,kerrickstaley/clutter-vala,kerrickstaley/clutter-vala,heysion/clutter-clone,heysion/clutter-clone,djdeath/clutter-android,jigpu/clutter,djdeath/clutter-multithreaded,djdeath/clutter-android,dlespiau/clutter,GNOME/clutter,collects/clutter,collects/clutter,jigpu/clutter,spatulasnout/clutter,djdeath/clutter-android,jigpu/clutter,spatulasnout/clutter,djdeath/clutter,Distrotech/clutter,collects/clutter,heysion/clutter-clone,djdeath/clutter-android,djdeath/clutter-android,djdeath/clutter-multithreaded