[Mac/iOS/GN] Place a version in the command of toolchain tools implemented using scripts.

build/toolchain/mac/get_tool_mtime.py

Index: build/toolchain/mac/get_tool_mtime.py
diff --git a/build/toolchain/mac/get_tool_mtime.py b/build/toolchain/mac/get_tool_mtime.py
new file mode 100644
index 0000000000000000000000000000000000000000..2634e561d147935e473637f7d9f0922a15c88b47
--- /dev/null
+++ b/build/toolchain/mac/get_tool_mtime.py
@@ -0,0 +1,14 @@
+# Copyright 2016 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 sys
+
+# Usage: python get_tool_mtime.py file
+#
+# Prints the file modification time of the file referenced by the first
+# argument.
+
+if __name__ == '__main__':
+  print os.path.getmtime(sys.argv[1])