MSVC does not support inline assembly (clang-cl does).

Those two functions needs to be implemented using C++ only. Implemented
a version for MSVC only, based on an intrinsic (that guarantees load,
even with optimization) available for any architecture.

Bug: v8:13312
Change-Id: I3aa4eac03c099535c5d3a9a40221bd5f8bbcb0d1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3913036Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83407}