cogl-framebuffer: Add some missing GL defines
cogl-framebuffer: Add some missing GL defines

Since 755cce33a7 the framebuffer code is using the GL enums
GL_DEPTH_ATTACHMENT and GL_DEPTH_COMPONENT16. These aren't available
directly under GLES except with the OES suffix so we need to define
them manually as we do with the other framebuffer constants.

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