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

build/run_build_tests.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.
 
 """Run all python tests in this directory."""
 
 import sys
 import unittest
 
 MODULES = [
     'directory_storage_test',
     'gsd_storage_test',
     'hashing_tools_test',
     'local_storage_cache_test',
 ]
 
 suite = unittest.TestLoader().loadTestsFromNames(MODULES)
 result = unittest.TextTestRunner(verbosity=2).run(suite)
 if result.wasSuccessful():
   sys.exit(0)
 else:
   sys.exit(1)