[infra] Remove dependence on //third_party/gyp/pylib/gyp/mac_tool.py

build/toolchain/mac/setup_toolchain.py

-# Copyright (c) 2013 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 os
-import stat
-import sys
-
-def CopyTool(source_path):
-  """Copies the given tool to the current directory, including a warning not
-  to edit it."""
-  with open(source_path) as source_file:
-    tool_source = source_file.readlines()
-
-  # Add header and write it out to the current directory (which should be the
-  # root build dir).
-  out_path = 'gyp-mac-tool'
-  with open(out_path, 'w') as tool_file:
-    tool_file.write(''.join([tool_source[0],
-                             '# Generated by setup_toolchain.py do not edit.\n']
-                            + tool_source[1:]))
-  st = os.stat(out_path)
-  os.chmod(out_path, st.st_mode | stat.S_IEXEC)
-
-# Find the tool source, it's the first argument, and copy it.
-if len(sys.argv) != 2:
-  print "Need one argument (mac_tool source path)."
-  sys.exit(1)
-CopyTool(sys.argv[1])