message: add copyright to trailing-comment.py
diff: @@ -11,6 +11,9 @@ becomes:
  // This is a very long comment explaining what this function does.
  void my_func(int param);
  +Copyright (c) 2017 The Bitcoin Unlimited developers
  +Distributed under the MIT software license, see the accompanying
  +file COPYING or http://www.opensource.org/licenses/mit-license.php.
  """
  import pdb
  import sys
  