GN: Add targets for AppRTCDemo on Mac+iOS

webrtc/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.
 
 # TODO(kjellander): Rebase this to webrtc/build/common.gypi changes after r6330.
 
@@ skipping 216 matching lines @@
     ]
   }
 
   if (use_libfuzzer || use_drfuzz || use_afl) {
     # Used in Chromium's overrides to disable logging
     defines += [ "WEBRTC_UNSAFE_FUZZER_MODE" ]
   }
 }
 
 config("common_objc") {
-  cflags = [ "-Wobjc-missing-property-synthesis" ]
-
+  libs = [ "Foundation.framework" ]
   precompiled_header = "sdk/objc/WebRTC-Prefix.pch"
   precompiled_source = "sdk/objc/WebRTC-Prefix.pch"
 }
 
 if (!is_ios || !build_with_chromium) {
   source_set("webrtc") {
     sources = [
       "call.h",
       "config.h",
       "transport.h",
@@ skipping 525 matching lines @@
     if (is_ios || (is_mac && target_cpu != "x86")) {
       defines = [ "CARBON_DEPRECATED=YES" ]
     }
     if (is_clang) {
       # Suppress warnings from the Chromium Clang plugin.
       # See http://code.google.com/p/webrtc/issues/detail?id=163 for details.
       configs -= [ "//build/config/clang:find_bad_constructs" ]
     }
   }
 }