Shader binary functions

Re-add the shader/program binary functions to Qt 4.7 that were removed from Qt 4.6 in change cabfa68f3e37e79a18775a9970f6d166e75ece07 and perform a new API review to ensure consistency with the source code based API.

Separately, add exported private API to 4.6.x to allow third parties to set the "compiled" and "linked" flags from their own code that calls the binary GL functions directly.