Revert of Remove the rtc_relative_path GYP variable and similar defines

webrtc/webrtc_tests.gypi

 # Copyright (c) 2013 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.
 {
   'targets': [
     {
@@ skipping 252 matching lines @@
       'target_name': 'webrtc_nonparallel_tests',
       'type': '<(gtest_target_type)',
       'sources': [
         'base/nullsocketserver_unittest.cc',
         'base/physicalsocketserver_unittest.cc',
         'base/socket_unittest.cc',
         'base/socket_unittest.h',
         'base/socketaddress_unittest.cc',
         'base/virtualsocket_unittest.cc',
       ],
+      'defines': [
+        'GTEST_RELATIVE_PATH',
+      ],
       'dependencies': [
         '<(DEPTH)/testing/gtest.gyp:gtest',
         'base/base.gyp:rtc_base',
         'test/test.gyp:test_main',
       ],
       'conditions': [
         ['OS=="android"', {
           'dependencies': [
             '<(DEPTH)/testing/android/native_test.gyp:native_test_native_code',
           ],
@@ skipping 169 matching lines @@
             'build/isolate.gypi',
           ],
           'sources': [
             'webrtc_perf_tests.isolate',
           ],
         },
       ],
     }],
   ],
 }