softpipe: Add support for reporting shader-db output.

In doing the softpipe NIR and NIR-to-TGSI transition, I want to make sure
I don't make shaders significantly worse, so I need shader-db output.

Reviewed-by: Dave Airlie <airlied@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6018>
3 files changed