bsc: Add code responsible for connecting, reconnecting to the MSC

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.
diff --git a/openbsc/src/bsc/osmo_bsc_main.c b/openbsc/src/bsc/osmo_bsc_main.c
index 649f0a5..90c4044 100644
--- a/openbsc/src/bsc/osmo_bsc_main.c
+++ b/openbsc/src/bsc/osmo_bsc_main.c
@@ -224,6 +224,11 @@
 		}
 	}
 
+	if (osmo_bsc_msc_init(bsc_gsmnet) != 0) {
+		LOGP(DNAT, LOGL_ERROR, "Failed to start up. Exiting.\n");
+		exit(1);
+	}
+
 	signal(SIGINT, &signal_handler);
 	signal(SIGABRT, &signal_handler);
 	signal(SIGUSR1, &signal_handler);