st/mesa: add support for GL_EXT_window_rectangles

Make sure to pass the requisite information in draws, blits, and clears
that work on the context's draw buffer.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
11 files changed