Replace test_support_main by test_main and get rid of test_support_main_threaded_mac

webrtc/modules/rtp_rtcp/BUILD.gn

 # Copyright (c) 2014 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.
 
 import("../../build/webrtc.gni")
 
@@ skipping 185 matching lines @@
     testonly = true
 
     sources = [
       "test/testFec/average_residual_loss_xor_codes.h",
       "test/testFec/test_packet_masks_metrics.cc",
     ]
 
     deps = [
       ":rtp_rtcp",
       "//testing/gtest",
-      "//webrtc/test:test_support_main",
+      "//webrtc/test:test_main",
     ]
   }  # test_packet_masks_metrics
 }