st/dri2: Implement DRI2bufferDamageExtension

st/dri2: Implement DRI2bufferDamageExtension

Add a pipe_screen->set_damage_region() hook to propagate
set-damage-region requests to the driver, it's then up to the driver to
decide what to do with this piece of information.

If the hook is left unassigned, the buffer-damage extension is
considered unsupported.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Qiang Yu <yuq825@gmail.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>