Omit crashing bench on iOS Metal

Bug: skia:9799
Change-Id: I341a83b575a4e4595756c3ee055fcbc1418bc962
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/272636
Auto-Submit: Ben Wagner aka dogben <benjaminwagner@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
2 files changed