msc: add sdp to MNCC

SDP is added to the MNCC protocol in osmo-msc
Ie16f0804c4d99760cd4a0c544d0889b6313eebb7.
This patch adds SDP to the ttcn3 MNCC messaging.

These changes still work with current osmo-msc master that doesn't send SDP /
ignores received SDP in MNCC.

Change-Id: Ic9568c8927507e161aadfad1a4d20aa896d8ae30
diff --git a/library/mncc.h b/library/mncc.h
index 3e00db8..9aff948 100644
--- a/library/mncc.h
+++ b/library/mncc.h
@@ -265,6 +265,8 @@
 
 	unsigned char	lchan_type;
 	unsigned char	lchan_mode;
+
+	char		sdp[1024];
 };
 
 struct gsm_data_frame {
@@ -296,6 +298,8 @@
 	uint16_t	port;
 	uint32_t	payload_type;
 	uint32_t	payload_msg_type;
+
+	char		sdp[1024];
 };
 
 struct gsm_mncc_bridge {