_ReadWriteBarrier() is deprecated, and <atomic> has been available for
a while now.

Ports part of https://chromium-review.googlesource.com/c/chromium/src/+/2365092
to v8.

No behavior change.

Bug: chromium:1255114
Change-Id: I9954193a69dad9396a5e9e7450066382de2fb172
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3204827
Auto-Submit: Nico Weber <thakis@chromium.org>
Commit-Queue: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77258}