Debian change: write pid-file even using systemd.

debian/init

@@ -277,9 +277,8 @@ case "$1" in
 	stop_resolvconf
 	;;
   systemd-exec)
-#  --pid-file without argument disables writing a PIDfile, we don't need one with sytemd.
 # Enable DBus by default because we use DBus activation with systemd.
-	exec $DAEMON --keep-in-foreground --pid-file --enable-dbus \
+	exec $DAEMON --keep-in-foreground --enable-dbus \
 	    ${MAILHOSTNAME:+ -m $MAILHOSTNAME} \
 	    ${MAILTARGET:+ -t $MAILTARGET} \
 	    ${DNSMASQ_USER:+ -u $DNSMASQ_USER} \