openpgm: new package

OpenPGM is an open source implementation of the Pragmatic General
Multicast (PGM) specification in RFC 3208 available at www.ietf.org.
It is required for PGM/EPGM support in ZeroMQ library.

Signed-off-by: Alexander Lukichev <alexander.lukichev@gmail.com>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>