Get tests working on systems that only support IPv6.

webrtc/base/nethelpers.h

 /*
  *  Copyright 2008 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.
  */
 
@@ skipping 41 matching lines @@
   SocketAddress addr_;
   std::vector<IPAddress> addresses_;
   int error_;
 };
 
 // rtc namespaced wrappers for inet_ntop and inet_pton so we can avoid
 // the windows-native versions of these.
 const char* inet_ntop(int af, const void *src, char* dst, socklen_t size);
 int inet_pton(int af, const char* src, void *dst);
 
+bool HasIPv4Enabled();
 bool HasIPv6Enabled();
 }  // namespace rtc
 
 #endif  // WEBRTC_BASE_NETHELPERS_H_