GN: Change rtc_source_set targets --> rtc_static_library

webrtc/test/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")
 import("//build/config/ui.gni")
 if (is_android) {
   import("//build/config/android/rules.gni")
 }
 
-rtc_source_set("test") {
+group("test") {
   testonly = true
 
   deps = [
     ":field_trial",
     ":rtp_test_utils",
     ":test_common",
     ":test_renderer",
     ":test_support",
     ":test_support_main",
     ":test_support_unittests",
@@ skipping 369 matching lines @@
     suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
   }
 
   deps = [
     ":test_support",
     ":video_test_common",
     "../modules/media_file",
     "//testing/gtest",
   ]
 }