INT 61 - Banyan VINES - CLOSE SOCKET                                            
	AX = 000Fh subfn 0004h
	CX:BX -> request block (see #03449)
	DX = application's data segment (should be = CX)
	ES = DS
Return: AX = status
	    0000h successful
	    00A5h resource not available
Desc:	Closes a socket identified by its socket handle


Format of request block:
Offset	Size	Description	(Table 03449)
 00h	WORD	0004h
 02h	WORD	magic number (FEFEh)
 04h	WORD	buffer for return code (set to 0 before calling)
 06h	WORD	reserved (will be set to client DS)
 08h	WORD	reserved (obviously not used; set to 0 before calling)
 0Ah	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	far pointer to socket handle (2 bytes)
 0Eh	WORD	process handle (see AX=000Fh/SF=0008h)