On ppc64 and s390x, Liftoff is not implemented yet, so if a Liftoff
compilation unit finishes after all top-tier units (hence after the "top
tier finished" callback), it will still increase the turbofan counter.

R=clemensb@chromium.org, ecmziegler@chromium.org

Bug: chromium:1092417
Change-Id: I0b99061f26851288f1abb8fcc3a30ca92a55164e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2429564Reviewed-by: Emanuel Ziegler <ecmziegler@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Junliang Yan <junyan@redhat.com>
Cr-Commit-Position: refs/heads/master@{#70123}