Seems to be failing on Mac Pro FYI Release (AMD). Unclear exactly the
scope of the problem so suppress it on all Mac AMD for now.

Bug: angleproject:2747
Change-Id: I7a5da00b9056839f3ed01fc4c83fa7993019bda7
Reviewed-on: https://chromium-review.googlesource.com/1192550Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>