mgcp: Add tests for payload types in MGCP messages

These tests mainly check whether the SDP parsing works properly by
looking at the payload type detected.

Sponsored-by: On-Waves ehf
diff --git a/openbsc/tests/mgcp/mgcp_test.ok b/openbsc/tests/mgcp/mgcp_test.ok
index 429e0df..3bfd78b 100644
--- a/openbsc/tests/mgcp/mgcp_test.ok
+++ b/openbsc/tests/mgcp/mgcp_test.ok
@@ -17,6 +17,7 @@
 Testing MDCX2
 Testing CRCX
 Testing MDCX3
+Testing MDCX4
 Testing DLCX
 Testing CRCX_ZYN
 Testing EMPTY