actor: Use the correct return value
actor: Use the correct return value

The get_z_rotation_gravity() method returns an enumeration value, not a
floating point value.

Signed-off-by: Emmanuele Bassi <ebassi@gnome.org>

https://bugzilla.gnome.org/show_bug.cgi?id=694187

collects/clutter,djdeath/clutter,heysion/clutter-clone,djdeath/clutter,Distrotech/clutter,ebassi/clutter,djdeath/clutter-android,jigpu/clutter,djdeath/clutter,jigpu/clutter,jigpu/clutter,Distrotech/clutter,djdeath/clutter-android,collects/clutter,jigpu/clutter,jigpu/clutter,GNOME/clutter,ebassi/clutter,collects/clutter,Distrotech/clutter,djdeath/clutter,djdeath/clutter,Distrotech/clutter,GNOME/clutter,djdeath/clutter-android,heysion/clutter-clone,ebassi/clutter,jigpu/clutter,djdeath/clutter-android,GNOME/clutter,heysion/clutter-clone,ebassi/clutter,ebassi/clutter,GNOME/clutter,collects/clutter,djdeath/clutter-android,heysion/clutter-clone,djdeath/clutter,collects/clutter,Distrotech/clutter,GNOME/clutter,heysion/clutter-clone,Distrotech/clutter