Add option to return non-segwit serialization via rpc

src/rpc/server.cpp

@@ -523,4 +523,9 @@ void RPCRunLater(const std::string& name, boost::function<void(void)> func, int6
     deadlineTimers.insert(std::make_pair(name, std::shared_ptr<RPCTimerBase>(timerInterface->NewTimer(func, nSeconds*1000))));
 }
 
+int RPCSerializationFlags()
+{
+    return 0;
+}
+
 CRPCTable tableRPC;