INT 21 - DOS 1+ - CLOSE FILE USING FCBsee File Control Block
	AH = 10h
	DS:DX -> File Control BlockA data record in the calling program's address space which is used by DOS 1.x functions to record the state of an open file.	See also INT 21h Function 13h. (see #01345)
Return: AL = status
	    00h successful
	    FFh failed
Notes:	a successful close forces all disk buffers used by the file to be
	  written and the directory entry to be updated
	not supported by MS Windows 3.0 DOSX.EXE DOS extender
SeeAlso: AH=0Fh,AH=16h,AH=3Eh