Pretty similar than other oses except we check LLVM/clang usage.
Upstreaming local FreeBSD patches.

Change-Id: Ife8447a9ff35e30a92134f65a2d8394d5123d9ab
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1910108
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65137}