INT 7A - Novell NetWare - IPXODI v2.12+ - SEND WITH CHECKSUM

	BX = 0020h
	ES:SI -> ECB (see #03810 at INT 7A/BX=0003h)
Return: DS,FLAGS preserved
	BX,BP corrupted (documented as potentially destroying all other regs)
Desc:	generate a checksum for the packet data and store it in the IPX
	  checksum field before transmitting the packet
SeeAlso: BX=001Fh,BX=0021h,BX=0022h,INT 2F/AX=7A2Fh