The CPPGC_BUILD_IN_V8 define (used for tracing) isn't propagated from
v8_base_without_compiler to cppgc_base, which breaks build with
perfetto. Instead use a gn args to specify standalone builds (defaulted
to false) and use that to choose the right tracing implementation.

Bug: chromium:1056170
Change-Id: I70bce819d45fb133b6f932a50a5d027e39f3e5b9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2555007
Auto-Submit: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71356}