extensions: libipt_ULOG: man page should mention NFLOG as replacement

Signed-off-by: Florian Westphal <fw@strlen.de>
extensions: libxt_connlabel: use libnetfilter_conntrack

Pablo suggested to make it depend on lnf-conntrack, and get rid of
the example config file as well.

The problem is that the file must be in a fixed path,
/etc/xtables/connlabel.conf, else userspace needs to "guess-the-right-file"
when translating names to their bit values (and vice versa).

Originally "make install" did put an example file into /etc/xtables/,
but distributors complained about iptables ignoring the sysconfdir.

So rather remove the example file, the man-page explains the format,
and connlabels are inherently system-specific anyway.

Signed-off-by: Florian Westphal <fw@strlen.de>