main/stasis_endpoints: Fix ContactStatusChange JSON for roundtrip_usec field

The JSON packing for the ContactStatusChange event forgot to include the
roundtrip_usec field. As a result, the field never showed up in any event,
even when the data was available. This patch corrects that error by properly
packing the JSON blob with the data.

Change-Id: I8df80da659a44010afbd48f645967518ff5daa17

main/stasis_endpoints.c

@@ -247,7 +247,7 @@ static struct ast_json *contactstatus_to_json(struct stasis_message *msg, const
 		return NULL;
 	}
 
-	json_final = ast_json_pack("{s: s, s: o, s: o, s: { s: s, s: s, s: s } } ",
+	json_final = ast_json_pack("{s: s, s: o, s: o, s: { s: s, s: s, s: s, s: s } } ",
 		"type", "ContactStatusChange",
 		"timestamp", ast_json_timeval(*tv, NULL),
 		"endpoint", json_endpoint,