Fix use-after-free timeout issue for L2TP and SSTP

src/Mayaqua/Network.c

@@ -16899,6 +16899,7 @@ TUBE *NewTube(UINT size_of_header)
 	t->SockEvent = NewSockEvent();
 
 	t->SizeOfHeader = size_of_header;
+	t->DataTimeout = 0;
 
 	return t;
 }

src/Mayaqua/Network.h

@@ -412,6 +412,7 @@ struct TUBE
 	bool IsInFlushList;					// Whether it is registered in the Tube Flush List
 	void *Param1, *Param2, *Param3;
 	UINT IntParam1, IntParam2, IntParam3;
+	UINT64 DataTimeout;
 };
 
 // Data that is to send and to receive in the tube