This changes gcmole's bootstrapping script so that it always creates
binaries that link libstdc++ statically (both plugin and Clang) and do
not link against unneeded libraries (only Clang). For deployment of
gcmole on our infrastructure, it is much easier to have fewer external
dependencies.

R=machenbach@chromium.org
BUG=v8:8813

Change-Id: If6f2f3cc3b1f661f7dafbb406eaaf2e639981640
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1526002Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60262}