Instead of using hard-coded clang flags (which are missing important
flags and are thus not that useful), use the flags for some unrelated
C++ file.

R=ahaas@chromium.org

No-Try: true
Change-Id: I516df9431e8aad1a63e832aa28450475193fd404
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1955549
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65387}