Previous implementation uses SSRC as IPv4 address that is same behaviour
of Kenwood's NXDN repeater.
RFC 3350 RTP protocol recommends SSRC uses random number.
So I use MT19937 random number generator instead of IP address.
And if this is no problem, I will do two changes.
- replace rand() in DMRNetwork.cpp and DStarNetwork.cpp to MT19937
- remove getLocalAddress() in UDPSocket.cpp
