These new entries will need to be updated once more internal
formats are available, but this will do for now.

Also added the possibility to query the Framebuffer 0 for GL_BACK,
GL_DEPTH and GL_STENCIL, as is allowed by OpenGL ES 3.0.

Finally, added a missing break in the GL_DEPTH_STENCIL_ATTACHMENT case.

Change-Id: Ifc32cc306c762ff58f9a9fe6608f7c19d3901c31
Reviewed-on: https://swiftshader-review.googlesource.com/3632Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>