[PATCH] Source address selection for nsd-notify, +relevant nsdc changes

nsd-notify, prior to this patch, lets the OS select the source address;
unfortunately, the OS-selected address in many cases will differ from
the address nsd listens on (in my configuration, I have a server with
three IP addresses - recursive DNS, authorative DNS, host IP address;
NSD just listens on the authorative one).

This patch adds a '-s' options to nsd-notify allowing selection of
source address; multiple -s options may be given, nsd-notify will try to
bind to them in order. It supports setting both the v4 and v6 source
address.

The manpage is updated accordingly.

nsdc is modified to pass nsd-notify an IP address included in the config
file, except for 127.0.0.1 and ::1.

Index: nsdc.sh.in