MGCP: Connection Identifiers are hex strings

The MGCP spec in RFC3435 is quite clear: Connection Identifiers are
hexadecimal strings of up to 32 characters. We should not print and
parse them as integers on either client or server.

Change the internal uint32_t representation of connection identifiers
to a string representation in the client and also in the server.

Closes: OS#2649
Change-Id: I0531a1b670d00cec50078423a2868207135b2436
diff --git a/src/libosmo-mgcp/mgcp_osmux.c b/src/libosmo-mgcp/mgcp_osmux.c
index 09b2636..5030812 100644
--- a/src/libosmo-mgcp/mgcp_osmux.c
+++ b/src/libosmo-mgcp/mgcp_osmux.c
@@ -573,7 +573,7 @@
 	if (conn->osmux.state != OSMUX_STATE_ENABLED)
 		return;
 
-	LOGP(DLMGCP, LOGL_INFO, "Releasing connection %u using Osmux CID %u\n",
+	LOGP(DLMGCP, LOGL_INFO, "Releasing connection %s using Osmux CID %u\n",
 	     conn->conn->id, conn->osmux.cid);
 	osmux_xfrm_input_close_circuit(conn->osmux.in, conn->osmux.cid);
 	conn->osmux.state = OSMUX_STATE_DISABLED;