Intel Optimization Manual update the suggestion for code alignment from 16B to 16B(for codes in legacy decoded pipeline) and 64B (for codes in Decoded Icache).

Since the loop often goes to the Decoded Icache, so align the loop header at 64B.

Change-Id: I1092e6dd5ea5937d5512865ce847ee00d1e8cb21
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3017311
Commit-Queue: Hao A Xu <hao.a.xu@intel.com>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75807}