.. which was previously broken due to 1. a hardcoded impl names list
and 2. the addition of a new impl (riscv).

The new solution prevents this in the future by basing both enum and
name generation on a macro list.

Bug: v8:11572
Change-Id: Ieb2134c9ecf3729633b76e4a30e7ddceba396328
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2764752
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73455}