IPv6 support for syslog

Hello All,

Some time ago, a patch was submitted to the Fedora sysklogd to provide
IPv6 support. This patch, apparently, came from the freebsd syslogd.
The patch was subsequently lost although the old Fedora RPM can still be
found.

I took that patch, the current freebsd sources and a dash of salt to
produce a new patch which I have attached.

The patch does two things: it will arrange for syslogd to listen on an
IPv6 socket in addition to the IPv4 socket and it uses getaddrinfo() and
getnameinfo() rather than gethostby[name|addr] and getservbyname. It
would be possible to use a single socket that accepts both IPv6 and IPv4
datagrams, but this would mean that numeric IPv4 addresses would be
prefixed with ::ffff and this could cause some confusion -- and I'm also
not sure that everything that sysklogd runs on has a dual stack like that.

I've also introduced the -4, -6 and -A with the same meanings that the
freebsd and rsyslog variants do.

This patch arose out of a request from someone else and seems to be
generally useful.

jch