(#787434) modify group of /var/run/clamd.scan
After 6 years and reading some reports as bug #787434, #1284253, we need
that /var/run/clamd.scan can be read from oher users, changing directory
ownerchip to virusgroup, makes clamilt and users of virusgroup group,
access to directory and read the socket.
This solution also assure that regular user don't have access to the
directory .