INT 2F - Windows95 - DOS KERNEL - (DE)ALLOCATE HMA MEMORY BLOCK

	AX = 4A03h
	CX = segment of block's owner???
	DL = subfunction
	    00h allocate block
		BX = number of bytes
		Return: DI=FFFFh if unable to allocate
			ES:DI -> allocated block
	    01h resize block
		ES:DI -> previously-allocated block
		BX = new size in bytes (must be less than original size???)
		Return: DI=FFFFh if unable to allocate
			ES:DI -> reallocated block
		Note:	the contents of the original block are NOT copied
	    02h free block???
		ES:DI -> block to be freed
Note:	in MS-DOS 7.x, function 4A02h is implemented by calling this function
	  with DL=00h
SeeAlso: AX=4A02h