These options have been added to the 'git cl config' subcommand.
--deactivate-update tells git cl not to update the values inside
.git/config from the codereview.settings file. --activate-update does
the opposite.

This is designed for testing/development purposes only, for example, to
be able to change the rietveld URL.

BUG=327901

Review URL: https://codereview.chromium.org/104043008

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@242943 0039d316-1c4b-4281-b951-d872f2087c98