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

pnacl/driver/tests/translate_options_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.
 
 """Tests of the pnacl driver.
 
 This tests that pnacl-translate options pass through to LLC correctly,
 and are overridden correctly.
 """
 
@@ skipping 238 matching lines @@
           [mattr_pat])
       self.checkLLCTranslateFlags(
           pexe,
           self.platform,
           [mattr_flags, '--pnacl-sb'],
           ['StreamInitWithOverrides.*' + mattr_pat + '.*-mcpu=.*'])
 
 
 if __name__ == '__main__':
   unittest.main()