git-cl: Add parallel option to git-cl land.

It is used by CMDland but it was not declared and is causing failures.

TBR=agable@chromium.org

Bug: 832566
Change-Id: Ia8ba5df458f9a39e415b7a9495dc338def0b16a5
Reviewed-on: https://chromium-review.googlesource.com/1013056
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>
Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Reviewed-by: Michael Moss <mmoss@chromium.org>
diff --git a/git_cl.py b/git_cl.py
index a58ceae..72b300f 100755
--- a/git_cl.py
+++ b/git_cl.py
@@ -5125,6 +5125,9 @@
                     help="external contributor for patch (appended to " +
                          "description and used as author for git). Should be " +
                          "formatted as 'First Last <email@example.com>'")
+  parser.add_option('--parallel', action='store_true',
+                    help='Run all tests specified by input_api.RunTests in all '
+                         'PRESUBMIT files in parallel.')
   auth.add_auth_options(parser)
   (options, args) = parser.parse_args(args)
   auth_config = auth.extract_auth_config_from_options(options)