There's a report about a nightly "crash" when users download, compile
from source, and replace their distro's mindlnad binary. This is because
the Debian package includes a patch that uses SIGUSR2 to reopen the log
file and sends SIGUSR2 from logrotate instead of just using the
"copytruncate" logrotate option. Then logrotate sends SIGUSR2 at 6:25AM,
which causes us to abort due to the unhandled signal.
I don't want to sacrifice SIGUSR2 just for log rotation, especially when
we already do some reload operations on SIGHUP. So to avoid this
Debian/Ubuntu issue, we'll explicitly ignore SIGUSR2, and add log file
reopening to the SIGHUP handler. Then hopefully a future Debian package
version will remove the SIGUSR2 patch and use SIGHUP instead (or
copytruncate).
Fixes: SF Bug #313 (log rotation kills minidlna service)
