src: remove unused function declaration

PR-URL: https://github.com/nodejs/node/pull/8878
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ilkka Myller <ilkka.myller@nodefield.com>
Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>

src/udp_wrap.h

@@ -27,7 +27,6 @@ class UDPWrap: public HandleWrap {
   static void Send6(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void RecvStart(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void RecvStop(const v8::FunctionCallbackInfo<v8::Value>& args);
-  static void GetSockName(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void AddMembership(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void DropMembership(const v8::FunctionCallbackInfo<v8::Value>& args);
   static void SetMulticastTTL(const v8::FunctionCallbackInfo<v8::Value>& args);