INT 21 - DR-DOS 3.41+ internal - SET ACCESS RIGHTS AND PASSWORD
        AX = 4303h
        CX = access rights
             bits 11-0: access rights (see AX=4302h)
             bit 15: new password is to be set
        DS:DX -> ASCIZ pathname
        [DTA] = new password if CX bit 15 is set (blank-padded to 8 characters)
Return: CF clear if successful
        CF set on error
            AX = error code
Note:   if the file is already protected, the old password must be added after
          the pathname, separated by a ";"
SeeAlso: AX=4454h