nfct: construct by passing handler

Signed-off-by Ken-ichirou MATSUZAWA <chamas@h4.dion.ne.jp>
nfct: introduce counter mode

This patch introduce counter mode, which aim for nfct-daemon.c in
libmnl working in ulogd.

Signed-off-by Ken-ichirou MATSUZAWA <chamas@h4.dion.ne.jp>