PRESUBMIT: Ignore external_bin/.

This is created for the external gsutil since r293320, and was creating
needless churn in presubmit tests when it is present.

R=pgervais@chromium.org,hinoka@google.com
BUG=434422

Review URL: https://codereview.chromium.org/831913003

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@293574 0039d316-1c4b-4281-b951-d872f2087c98

PRESUBMIT.py

@@ -18,6 +18,7 @@ def CommonChecks(input_api, output_api, tests_to_black_list):
   black_list = list(input_api.DEFAULT_BLACK_LIST) + [
       r'^cpplint\.py$',
       r'^cpplint_chromium\.py$',
+      r'^external_bin[\/\\].+',
       r'^python[0-9]*_bin[\/\\].+',
       r'^site-packages-py[0-9]\.[0-9][\/\\].+',
       r'^svn_bin[\/\\].+',