[group] avoid double evaluation of arguments in clutter_group_add
[group] avoid double evaluation of arguments in clutter_group_add

clutter_group_add would evaluate the actor argument twice, which is
bad if this is a function call creating a new actor and not a variable.

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