Issue 719:  Fix for TALOS-CAN-154

A RAR file with an invalid zero dictionary size was not being
rejected, leading to a zero-sized allocation for the dictionary
storage which was then overwritten during the dictionary initialization.

Thanks to the Open Source and Threat Intelligence project at Cisco for
reporting this.
lzss_size(struct lzss *lzss)
{
  return lzss->mask + 1;
}

lzss_size(struct lzss *lzss)
{
  return lzss->mask + 1;
}
