INT D4 - PC-MOS/386 v3.0+ - FREE NATIVE MODE MEMORY BLOCK                       
	AH = 12h
	ES = selector for block to free
Return: CF clear if successful
	CF set on error
	    AX = error code (see #01680 at INT 21/AH=59h/BX=0000h)
SeeAlso: AH=10h,AH=11h,AH=13h,INT 38