Land: https://webrtc-codereview.appspot.com/678010/

Add -Wno-unused-private-field until all violations are fixed.

This is currently in chromium's build/common.gypi, but I'd like
to remove it from there.
Review URL: https://webrtc-codereview.appspot.com/680006

git-svn-id: http://webrtc.googlecode.com/svn/trunk@2485 4adac7df-926f-26a2-2b94-8c16560cd09d

src/build/common.gypi

@@ -183,6 +183,17 @@
           'WEBRTC_ANDROID_OPENSLES',
          ],
       }],
+      ['clang==1', {
+        'xcode_settings': {
+          'WARNING_CFLAGS': [
+            # TODO(thakis): Remove once all violations are fixed.
+            '-Wno-unused-private-field',
+          ],
+        },
+        'cflags': [
+          '-Wno-unused-private-field',
+        ]
+      }],
     ], # conditions
   }, # target_defaults
 }