clone: Remove unnecessary G_UNLIKELY macros
clone: Remove unnecessary G_UNLIKELY macros

A Clone:source property might be NULL, and we should not penalize
performance when we can just bail out early, because that would kind of
defeat the point.

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