rpcrt4: Set ReservedForRuntime to NULL in NdrClientInitializeNew.

dlls/rpcrt4/ndr_clientserver.c

@@ -57,6 +57,7 @@ void WINAPI NdrClientInitializeNew( PRPC_MESSAGE pRpcMessage, PMIDL_STUB_MESSAGE
   pRpcMessage->ProcNum = ProcNum | RPC_FLAGS_VALID_BIT;
   pRpcMessage->RpcInterfaceInformation = pStubDesc->RpcInterfaceInformation;
   pRpcMessage->RpcFlags = 0;
+  pRpcMessage->ReservedForRuntime = NULL;
   pRpcMessage->DataRepresentation = NDR_LOCAL_DATA_REPRESENTATION;
 
   pStubMsg->RpcMsg = pRpcMessage;