Fix iOS GN build and cleanup system_wrappers

webrtc/common_audio/BUILD.gn

Index: webrtc/common_audio/BUILD.gn
diff --git a/webrtc/common_audio/BUILD.gn b/webrtc/common_audio/BUILD.gn
index b01b31816bd9b7b060c337d57c91f825205a278c..fcf8403a62b1af96d52cb02834008612d8ad83fb 100644
--- a/webrtc/common_audio/BUILD.gn
+++ b/webrtc/common_audio/BUILD.gn
@@ -239,5 +239,11 @@ if (rtc_build_with_neon) {
 
     configs += [ "..:common_config" ]
     public_configs = [ "..:common_inherited_config" ]
+
+    if (is_clang) {
+      # Suppress warnings from Chrome's Clang plugins.
+      # See http://code.google.com/p/webrtc/issues/detail?id=163 for details.
+      configs -= [ "//build/config/clang:find_bad_constructs" ]
+    }
   }
 }