By default, if the parent of a process dies, the process gets SIGHUP
and is supposed to shut down.  This however doesn't work for MPD,
because MPD redefines SIGHUP with a different meaning (like most
daemons do).

To work around this, we configure the kernel to send SIGTERM instead
of SIGHUP.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1706