Try to make compare_build_artifacts.py a bit faster.

1. Don't create a temporary zip list just for element-wise
   comparison.

2. Only enter the streams loop if we don't end up throwing away
   all computation in it.

On my machine, reduces runtime on a synthetic benchmark
(comparing base_unittests and all deps between a release and a
debug component build) from 37s to 20s.

Bug: 314403
Change-Id: Id425c3fbab99981391ec9de8887defc00d0da0af
Reviewed-on: https://chromium-review.googlesource.com/c/1387609
Reviewed-by: Erik Chen <erikchen@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#618352}
1 file changed