QMP: Don't free async event's 'data'

The monitor_protocol_event() function will free the
event's data, this is wrong as 'data' management is up
to the caller.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

monitor.c

diff --git a/monitor.c b/monitor.c
index 3af1d5c..2403a97 100644
--- a/monitor.c
+++ b/monitor.c
@@ -365,8 +365,10 @@
     qmp = qdict_new();
     timestamp_put(qmp);
     qdict_put(qmp, "event", qstring_from_str(event_name));
-    if (data)
+    if (data) {
+        qobject_incref(data);
         qdict_put_obj(qmp, "data", data);
+    }
 
     monitor_json_emitter(mon, QOBJECT(qmp));
     QDECREF(qmp);