actor: Update the underallocations check
actor: Update the underallocations check

Add a failsafe against a NULL parent, to avoid a segfault when calling
clutter_actor_allocate() on the Stage.

We also need to deal with floating point values: straight comparison is
not going to cut it.

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