cogl-material: Fallback to BlendFunc if BlendFuncSeparate is unavailable
cogl-material: Fallback to BlendFunc if BlendFuncSeparate is unavailable

glBlendFuncSeparate is only available in OpenGL 1.4. If we
conditionally check for this then Clutter will work with OpenGL 1.2.

http://bugzilla.openedhand.com/show_bug.cgi?id=1875

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