Replace test_support_main by test_main and get rid of test_support_main_threaded_mac

webrtc/test/testsupport/mac/run_threaded_main_mac.h

-/*
- *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-/**
- * This file and its corresponding .mm file implement a main function on Mac.
- * It's useful if you need to access a webcam in your Mac application. The code
- * forks a worker thread which runs the below ImplementThisToRunYourTest
- * function, and uses the main thread to pump messages. That way we can run our
- * code in a regular sequential fashion and still pump events, which are
- * necessary to access the webcam for instance.
- */
-
-// Implement this method to do whatever you want to do in the worker thread.
-// The argc and argv variables are the unmodified command line from main.
-int ImplementThisToRunYourTest(int argc, char** argv);