znc: new package

ported patch from Cédric Chépied:
http://patchwork.ozlabs.org/patch/306896/



[Thomas: added comment explaining why we don't use <pkg>_AUTORECONF,
and use a more conventional syntax for <pkg>_DEPENDENCIES and
<pkg>_CONF_OPT.]

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>