Initial import of firewalk-gtk-1.0 into the NetBSD Packages Collection.

Initial import of firewalk-gtk-1.0 into the NetBSD Packages Collection.

Firewalking is a technique developed by Mike D. Schiffman and David E.
Goldsmith that employs traceroute-like techniques to analyze IP packet
responses to determine gateway ACL filters and map networks.
Firewalk the tool employs the technique to determine the filter rules
in place on a packet forwarding device.

This package was provided in PR 14020 by xs@nitric.net. I split it into
two separate packages, firewalk-gtk and firewalk, and modified it to use
buildlink functionality.