INT 21 - Phar Lap 386/DOS-Extender VMM v2.1c+ - FREE PHYSICAL MEMORY PAGES

	AX = 251Ch
	BH = preservation flag (00h preserve contents, 01h discard contents)
	EDX = number of pages to free
	BL = address type
	    00h linear address
		ECX = linear address of first page to be freed
	    01h pointer
		ES:ECX -> first page to be freed
Return: CF clear if successful
	CF set on error
	    EAX = error code
		08h memory error, swap space full, no VMM or DPMI
		09h invalid address