Initial import of dbeacon version 0.3.9.1 in the NetBSD Packages

Initial import of dbeacon version 0.3.9.1 in the NetBSD Packages
Collection.

dbeacon is a Multicast Beacon written in C++. The main purpose of
a beacon is to monitor other beacon's reachability and collect
statistics such as loss, delay and jitter between beacons. dbeacon
supports both IPv4 and IPv6 multicast, collecting information via
ASM and SSM.

dbeacon was originally only IPv6 capable, designed to be used in
the m6bone.