aco: add add_interference() helper

This won't add interferences between spill ids of different types and will
exit early if there's already an interference.

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5805>
1 file changed