Revert "GL_EXT_discard_framebuffer: fully disable color component invalidation"

This reverts commit 496e8b1995c43d8d0ecc9486b73abaddfd649aaf.

Change-Id: Ia8b240c3ae43121a032688d51973eb6a617be2e6
Revert "Partially re-enable GL_EXT_discard_framebuffer extension"

This reverts commit d55e3410b02119ba0b40036370a3d2b591f7a2b3.

Change-Id: I49166c6a953dc621fb19798c041b723d453505b1