Function win64_unwindinfo::RegisterNonABICompliantCodeRange() calls
LoadNtdllUnwindingFunctions() to dynamically load from ntdll a couple of
functions that are not available on Windows 7. Unfortunately there is a
race condition in LoadNtdllUnwindingFunctions() that can cause a crash
when multiple isolates are initialized concurrently.
This can be fixed using base::CallOnce().

Bug: v8:9204
Change-Id: I5c57708ab5f16e9ef9f897efce1ccdf591e2f828
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1623592Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Paolo Severini <paolosev@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#61757}