b561946497
If the surface already has a current backbuffer - say through a buffer_age query - we do not want to replace it in get_buffers, because it means the result we'd previously returned them is stale. If we already have a backbuffer set on the surface, keep it locked in no matter what until we hit SwapBuffers. Signed-off-by: Daniel Stone <daniels@collabora.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14873>