qobject: Update coccinelle script to catch Q{INC, DEC}REF

The recent commit b097efc0 used qobject_decref(QOBJECT(E)), even
though we already have QDECREF(E) for that purpose.  We can update
our coccinelle script to catch any future relapses; with that in
place, the rest of the patch is generated with:
 spatch --sp-file scripts/coccinelle/qobject.cocci \
        --macro-file scripts/cocci-macro-file.h --dir . --in-place
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <20170624181008.25497-3-eblake@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

monitor.c

@@ -3842,7 +3842,7 @@ static void handle_qmp_command(JSONMessageParser *parser, GQueue *tokens)
 
     req_json = qobject_to_json(req);
     trace_handle_qmp_command(mon, qstring_get_str(req_json));
-    qobject_decref(QOBJECT(req_json));
+    QDECREF(req_json);
 
     rsp = qmp_dispatch(cur_mon->qmp.commands, req);
 

scripts/coccinelle/qobject.cocci

@@ -3,6 +3,12 @@
 expression Obj, Key, E;
 @@
 (
+- qobject_incref(QOBJECT(E));
++ QINCREF(E);
+|
+- qobject_decref(QOBJECT(E));
++ QDECREF(E);
+|
 - qdict_put_obj(Obj, Key, QOBJECT(E));
 + qdict_put(Obj, Key, E);
 |