Implement AoIP, port to M3UA SIGTRAN (large addition and refactoring)

This was originally a long series of commits converging to the final result
seen in this patch. It does not make much sense to review the smaller steps'
trial and error, we need to review this entire change as a whole.

Implement AoIP in osmo-msc and osmo-bsc.

Change over to the new libosmo-sigtran API with support for proper
SCCP/M3UA/SCTP stacking, as mandated by 3GPP specifications for the IuCS and
IuPS interfaces.

From here on, a separate osmo-stp process is required for SCCP routing between
OsmoBSC / OsmoHNBGW <-> OsmoMSC / OsmoSGSN

jenkins.sh: build from libosmo-sccp and osmo-iuh master branches now for new
M3UA SIGTRAN.

Patch-by: pmaier, nhofmeyr, laforge
Change-Id: I5ae4e05ee7c57cad341ea5e86af37c1f6b0ffa77
diff --git a/include/openbsc/osmo_bsc.h b/include/openbsc/osmo_bsc.h
index 9e688fd..5ebea50 100644
--- a/include/openbsc/osmo_bsc.h
+++ b/include/openbsc/osmo_bsc.h
@@ -26,6 +26,7 @@
 
 	/* for audio handling */
 	uint16_t cic;
+	uint32_t rtp_ip;
 	int rtp_port;
 
 	/* for advanced ping/pong */
@@ -44,6 +45,9 @@
 	uint8_t new_subscriber;
 
 	struct bsc_filter_state filter_state;
+
+	/* Sigtran connection ID */
+	int conn_id;
 };
 
 struct bsc_api *osmo_bsc_api();
@@ -60,7 +64,7 @@
 int bsc_send_welcome_ussd(struct gsm_subscriber_connection *conn);
 
 int bsc_handle_udt(struct bsc_msc_data *msc, struct msgb *msg, unsigned int length);
-int bsc_handle_dt1(struct osmo_bsc_sccp_con *conn, struct msgb *msg, unsigned int len);
+int bsc_handle_dt(struct osmo_bsc_sccp_con *conn, struct msgb *msg, unsigned int len);
 
 int bsc_ctrl_cmds_install();