SIGKILL doesn't exist on Windows, but SIGTERM does.
For our purposes they do the same thing.

Bug: 962263
Change-Id: I16929cf7d1377cd81f71401a48b5a84fe54da493
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1608561Reviewed-by: Marc-Antoine Ruel <maruel@chromium.org>
Commit-Queue: Raul Tambre <raul@tambre.ee>
Auto-Submit: Raul Tambre <raul@tambre.ee>