aco/optimizer: Only set scc_needed when it is actually needed.

Not every p_cbranch uses the SCC, but our optimizer thought so.

Fixes: 8a32f57fff56b3b94f1b5589feba38016f39427c
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7677>
(cherry picked from commit 8bd3fefb74bb731d509f971cc89c687a0fd99feb)
2 files changed