Finer grained control of platforms that support threads are
enforced by chromium.

Bug: chromium:1167733
Change-Id: Ic34a4950aebf6ba394053b79df97b703af333636
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2810190Reviewed-by: Lutz Vahl <vahl@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Deepti Gandluri <gdeepti@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73919}