client: add missing mandatory SDP fields

The mcgp message generator function mgcp_msg_gen() lacks support
for the mandatory SDP fields (v)ersion, (o)rigin, (s)ession and
(t)ime.

- Automatically generate the missing fields when SDP is
  generated.

Change-Id: I5fbc31a17e8ac10c7cc5dbc31357b61e8920aaa5
Related: OS#2837
diff --git a/tests/mgcp_client/mgcp_client_test.ok b/tests/mgcp_client/mgcp_client_test.ok
index 4039bb0..00c7f7c 100644
--- a/tests/mgcp_client/mgcp_client_test.ok
+++ b/tests/mgcp_client/mgcp_client_test.ok
@@ -43,8 +43,12 @@
 I: 11

 M: sendrecv

 

+v=0

+s=-

+o=- 2f 23 IN IP4 127.0.0.1

 c=IN IP4 192.168.100.23

 m=audio 1234 RTP/AVP 255

+t=0 0

 
 Generated DLCX message:
 DLCX 3 23@mgw MGCP 1.0