build_time_stats: Include masters in build-type reports.

If the --build-type option was used to create a report, the master
builder values were left out of the results. I was able to verify both
the problem, and the fix with this report:

bin/build_time_stats --cred-dir <creds> --build-type chrome-pfq \
   --report stability

BUG=None
TEST=Unittests + above report.

Change-Id: I3b36f5cb6b80a542edf519fa596550f130e067b8
Reviewed-on: https://chromium-review.googlesource.com/334397
Commit-Ready: Don Garrett <dgarrett@chromium.org>
Tested-by: Don Garrett <dgarrett@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
1 file changed