MGCP: don't use dec_MGCP_Message to avoid (possible) TITAN bug

See https://www.eclipse.org/forums/index.php/t/1088893/ for details
diff --git a/mgw/MGCP_CodecPort.ttcn b/mgw/MGCP_CodecPort.ttcn
index d1b1d19..6fedeeb 100644
--- a/mgw/MGCP_CodecPort.ttcn
+++ b/mgw/MGCP_CodecPort.ttcn
@@ -38,7 +38,11 @@
 		pout.remPort := pin.remPort;
 		pout.locName := pin.locName;
 		pout.locPort := pin.locPort;
-		pout.msg := dec_MgcpMessage(oct2char(pin.msg));
+		/* FIXME: This should actually be the below:
+		   pout.msg := dec_MgcpMessage(oct2char(pin.msg)); - see
+		   https://www.eclipse.org/forums/index.php/t/1088893/
+		 */
+		pout.msg := { response := dec_MgcpResponse(oct2char(pin.msg)) };
 	} with { extension "prototype(fast)" };
 
 	private function MGCP_to_IPL4_Send(in MGCP_Send pin, out ASP_Send pout) {