Fix subscript[0] in netaddress.cpp

Author: JeremyRubin

src/netaddress.cpp

@@ -573,7 +573,7 @@ std::vector<unsigned char> CService::GetKey() const
 {
      std::vector<unsigned char> vKey;
      vKey.resize(18);
-     memcpy(&vKey[0], ip, 16);
+     memcpy(vKey.data(), ip, 16);
      vKey[16] = port / 0x100;
      vKey[17] = port & 0x0FF;
      return vKey;