monitor: Assert qmp_schema_json[] is sane

qmp_query_qmp_schema() parses qmp_schema_json[] with
qobject_from_json().  This must not fail, so pass &error_abort.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Message-Id: <1488317230-26248-17-git-send-email-armbru@redhat.com>

monitor.c

@@ -953,7 +953,7 @@ EventInfoList *qmp_query_events(Error **errp)
 static void qmp_query_qmp_schema(QDict *qdict, QObject **ret_data,
                                  Error **errp)
 {
-    *ret_data = qobject_from_json(qmp_schema_json, NULL);
+    *ret_data = qobject_from_json(qmp_schema_json, &error_abort);
 }
 
 /*