Revert of Remove the rtc_relative_path GYP variable and similar defines

webrtc/build/common.gypi

 # 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 contains common settings for building WebRTC components.
 
@@ skipping 46 matching lines @@
     'build_with_chromium%': '<(build_with_chromium)',
     'build_with_mozilla%': '<(build_with_mozilla)',
     'webrtc_root%': '<(webrtc_root)',
     'apk_tests_path%': '<(apk_tests_path)',
     'test_runner_path': '<(DEPTH)/webrtc/build/android/test_runner.py',
     'modules_java_gyp_path%': '<(modules_java_gyp_path)',
     'webrtc_vp8_dir%': '<(webrtc_vp8_dir)',
     'webrtc_vp9_dir%': '<(webrtc_vp9_dir)',
     'include_ilbc%': '<(include_ilbc)',
     'include_opus%': '<(include_opus)',
+    'rtc_relative_path%': 1,
     'external_libraries%': '0',
     'json_root%': '<(DEPTH)/third_party/jsoncpp/source/include/',
     # openssl needs to be defined or gyp will complain. Is is only used when
     # when providing external libraries so just use current directory as a
     # placeholder.
     'ssl_root%': '.',
 
     # The Chromium common.gypi we use treats all gyp files without
     # chromium_code==1 as third party code. This disables many of the
     # preferred warning settings.
@@ skipping 153 matching lines @@
          ],
       }],
       ['have_dbus_glib==1', {
         'defines': [
           'HAVE_DBUS_GLIB',
          ],
          'cflags': [
            '<!@(pkg-config --cflags dbus-glib-1)',
          ],
       }],
+      ['rtc_relative_path==1', {
+        'defines': ['EXPAT_RELATIVE_PATH',],
+      }],
       ['os_posix==1', {
         'configurations': {
           'Debug_Base': {
             'defines': [
               # Chromium's build/common.gypi defines _DEBUG for all posix
               # _except_ for ios & mac.  The size of data types such as
               # pthread_mutex_t varies between release and debug builds
               # and is controlled via this flag.  Since we now share code
               # between base/base.gyp and build/common.gypi (this file),
               # both gyp(i) files, must consistently set this flag uniformly
@@ skipping 248 matching lines @@
           # For access to standard POSIXish features, use WEBRTC_POSIX instead
           # of a more specific macro.
           'defines': [
             'WEBRTC_POSIX',
           ],
         }],
       ],
     },
   }, # target_defaults
 }