radeon/ac: add ac_emit_imsb helper.

We want to use a different intrinsic on newer llvm, so move this
code to a shared area.

Reviewed-by: Edward O'Callaghan <funfunctor@folklore1984.net>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2 files changed