Fix read-from-NULL-pointer crashes when command line option arguments
are missing from long options --syslog-tag, --timestamp-date, or
--db-cachesize (the short option equivalents were unaffected); or when
BOGODIR/BOGOFILTER_HOME/HOME environment variables are all three
missing when running bogotune. (This is all under the invoking user's
control and not believed to be security relevant.)
Reported by Alexandre Rebert, found within the Mayhem project he is with.
Obtained from: http://svn.code.sf.net/p/bogofilter/code/trunk