Remove python bindings unittests from the build.

mojo/python/tests/system_unittest.py

 # Copyright 2014 The Chromium 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 random
 import sys
 import time
 import unittest
 
-# Setup sys path
-for path in sys.argv[1:]:
-  sys.path.append(path)
-
 # pylint: disable=F0401
 from mojo.embedder import init as init_embedder
 from mojo import system
 
 DATA_SIZE = 1024
 
 
 def get_random_buffer(size):
   random.seed(size)
   return bytearray(''.join(chr(random.randint(0, 255)) for i in xrange(size)))
@@ skipping 281 matching lines @@
     self.assertEquals(data, buf2.buffer)
     self.assertEquals(buf1.buffer, buf2.buffer)
 
 
 if __name__ == '__main__':
   suite = unittest.TestLoader().loadTestsFromTestCase(CoreTest)
   test_results = unittest.TextTestRunner(verbosity=0).run(suite)
   if not test_results.wasSuccessful():
     sys.exit(1)
   sys.exit(0)