effect: Fix up the class ABI
effect: Fix up the class ABI

Landing the paint-box branch accidentally added two slots to the
ClutterEffectClass vtable, plus the get_paint_volume() function
pointer. This is an ABI break from 1.4.

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