The roundss / vroundss instruction is only available on AVX or SSE4_1
hardware. Thus bring back the old code path with much longer code for
such old hardware.

R=tebbi@chromium.org

Bug: chromium:1314363
Change-Id: I79a58627c8b406817330e9f9601234cea28182c1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3578642Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79914}