pan/bi: Add constant modifier handling
Once we've merged the clauses' constants, we need to....
1. Swap where necessary so non-pcrel constants are correctly encoded.
2. Swap where necessary so pcrel constants are in canonical positions.
3. Force M1 values for pcrel constants and final single constants.
Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8354>