[cogl] Don't allow calling cogl_set_source_texture with an INVALID_HANDLE
[cogl] Don't allow calling cogl_set_source_texture with an INVALID_HANDLE

Although the underlying materials should allow layers with INVALID_HANDLES
it shouldn't be necissary to expose that via cogl_set_source_texture() and
it's easier to resolve a warning/crash here than odd artefacts/crashes later
in the pipeline.

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