For example, ^C (SIGINT) may leave the drive spinning and locked.
This may also happen if you try to write a too-large image to a disc
and burncd(8) exits with an I/O error.
Add signal handling by doing a CDRIOCFLUSH ioctl to attempt to leave
burner in a sane state when burning is interrupted with SIGHUP, SIGINT,
SIGTERM, or in case an I/O error occurs during write.
Note, that blanking will still continue after interrupt but it seems to
finish correctly even after burncd(8) has quit.
Also, while I'm here bump WARNS to "6".
PR: 48730
Submitted by: Jaakko Heinonen <jh@saunalahti.fi>
