**/*.py: use /usr/bin/env to find python

src/trusted/validator_ragel/gen_dfa_test.py

-#!/usr/bin/python
+#!/usr/bin/env python
 # Copyright (c) 2012 The Native Client Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import sys
 import unittest
 
 import def_format
 import gen_dfa
 
@@ skipping 615 matching lines @@
 
   def test_instruction_definitions(self):
     def_filenames = sys.argv[1:]
     assert len(def_filenames) > 0
     for filename in def_filenames:
       list(gen_dfa.ParseDefFile(filename))
 
 
 if __name__ == '__main__':
   unittest.main(argv=[sys.argv[0], '--verbose'])