[cogl-texture-2d-sliced] allow COGL_FORMAT_ANY with _new_with_size()
[cogl-texture-2d-sliced] allow COGL_FORMAT_ANY with _new_with_size()

It's useful when initialzing offscreen draw buffers to be able to ask
Cogl to create a texture of a given size and with the default internal
pixel format.

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