Get/set file attributes (INT 21h, 43h - CHMOD)

        Entry:
          AH = 43h
          AL = 0 = get file attributes
               1 = set file attributes
                   CX = file attribute bits
                       xxxx xxx1 xxxx xxxx  Shareable (Novell Netware)
                       xxxx xxxx xx1x xxxx  written since backup
                       xxxx xxxx xxx1 xxxx  subdirectory
                       xxxx xxxx xxxx 1xxx  volume label
                       xxxx xxxx xxxx x1xx  system file
                       xxxx xxxx xxxx xx1x  hidden file
                       xxxx xxxx xxxx xxx1  read only
          DX = pointer to ASCIIZ file name
        Return:
          CF = 1 if error
                  AX = Error Code if any
          CX = file attributes on get