We were already using it to define the SSE instructions.

Bug: v8:10933
Change-Id: I8c70c027449ee8b0d00a06298087310ced11cafc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2470200Reviewed-by: Bill Budge <bbudge@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70516}