GN: Add missing config //webrtc:common_objc for rtc_sdk_common_objc

webrtc/sdk/BUILD.gn

 # Copyright 2016 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")
 if (is_mac) {
   import("//build/config/mac/mac_sdk.gni")
   import("//build/config/mac/rules.gni")
 }
 if (is_ios) {
   import("//build/config/ios/rules.gni")
 }
 
 if (is_ios || (is_mac && mac_deployment_target == "10.7")) {
   config("rtc_sdk_common_objc_config") {
     include_dirs = [
       "objc/Framework/Classes",
       "objc/Framework/Headers",
     ]
   }
 
   rtc_static_library("rtc_sdk_common_objc") {
     deps = [
       "../base:rtc_base",
     ]
-    configs += [ "//build/config/compiler:enable_arc" ]
+    configs += [
+      "..:common_objc",
+      "//build/config/compiler:enable_arc",

[tkchin_webrtc, 2016/10/06 20:50:38]

enable_arc should be a common objc config I think. There shouldn't be instances
of non-arc code for targets that currently use common_objc that I know of.

[kjellander_webrtc, 2016/10/07 05:09:29]

If that was possible we certainly should do that. However configs cannot include
other configs in GN, so it's not possible. The workaround for that would be to
introduce our own template for this, but that would mean at least two templates
since both rtc_static_library and rtc_test targets use this. So I won't do it in
this CL at least.

+    ]
     public_configs = [ ":rtc_sdk_common_objc_config" ]
     sources = [
       "objc/Framework/Classes/NSString+StdString.h",
       "objc/Framework/Classes/NSString+StdString.mm",
       "objc/Framework/Classes/RTCDispatcher.m",
       "objc/Framework/Classes/RTCFieldTrials.mm",
       "objc/Framework/Classes/RTCLogging.mm",
       "objc/Framework/Classes/RTCMetrics.mm",
       "objc/Framework/Classes/RTCMetricsSampleInfo+Private.h",
       "objc/Framework/Classes/RTCMetricsSampleInfo.mm",
@@ skipping 286 matching lines @@
       public_configs = [ ":rtc_sdk_common_objc_config" ]
 
       if (is_clang) {
         # Suppress warnings from the Chromium Clang plugins.
         # See http://code.google.com/p/webrtc/issues/detail?id=163 for details.
         configs -= [ "//build/config/clang:find_bad_constructs" ]
       }
     }
   }
 }