INT 2F U - DOS 3.0+ internal - MAKE BUFFER MOST RECENTLY USED                   
	AX = 120Fh
	DS:DI -> disk buffer
	SS = DOS DS (must be using a DOS internal stack)
Return: DS:DI -> next buffer in buffer list
Desc:	move the indicated buffer to the end of the disk buffer chain (least-
	  recently used is first); under DOS 3.3, the buffer is then moved to
	  the start of the disk buffer chain if it was marked unused
Note:	this function is the same as AX=1207h except that it returns a
	  pointer to the buffer following the specified buffer in the buffer
	  chain
SeeAlso: AX=1207h