Revert of mojo: Add a runloop utility in python

mojo/public/python/src/python_system_helper.h

-// 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.
-
-#ifndef MOJO_PUBLIC_PYTHON_SRC_PYTHON_SYSTEM_HELPER_H_
-#define MOJO_PUBLIC_PYTHON_SRC_PYTHON_SYSTEM_HELPER_H_
-
-#include "Python.h"
-
-#include "mojo/public/cpp/bindings/callback.h"
-
-namespace mojo {
-
-// Create a mojo::Closure from a callable python object.
-mojo::Closure BuildClosure(PyObject* callable);
-
-// Initalize mojo::RunLoop
-void InitRunLoop();
-
-}  // namespace mojo
-
-#endif  // MOJO_PUBLIC_PYTHON_SRC_PYTHON_SYSTEM_HELPER_H_