In windows, even use clang build, the V8_LIBC_MSVCRT was set to indicate use MSVC runtime libraries. Change to use __clang__ to determine enable cpuid magic inline assembly or not.

Change-Id: I7372a27b311b695f019c5ff2d42b691d749eb607
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1715332Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Tianyou Li <tianyou.li@intel.com>
Cr-Commit-Position: refs/heads/master@{#62884}