Add the code that is forwarding data, from and to the MSC, also
handling ping/pong timers and authentication. Hook it into the
osmo_bsc. The code is only compile tested and ported from the
on-waves/bsc-master branch.
The grace code will decide if a given connection is allowed to
be made or if it is going to be rejected. For active connections
it is going to send a USSD message.
Add --enable-nat and --enable-osmo-bsc to build applications
requiring the Osmo SCCP library to be installed. We are not
using autodiscover as this is out of fashion.