)
Call IPX Look-Ahead handler with:
	AX = packet's destination socket
	DS:SI -> look-ahead structure (see #03010 at INT 2F/AX=C000h"LSL")
	DF clear
	interrupt disabled (must remain disabled)
Return: AX = packet use
	    0000h application want packet
		ES:SI -> ODI ECB (see #03011 at INT 2F/AX=C000h"LSL")
	    8001h application does not want packet
	ZF set if AX=0000h
	DS,DI,BP,SS,SP preserved
	interrupts disabled