qom: call class destructor before unparent

It seems more logical to have destruction flow start with the subclass
and move up to the base class.  This ensures object has a valid
canonical path when destructor is called.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

qom/object.c

@@ -363,12 +363,12 @@ static void object_property_del_child(Object *obj, Object *child, Error **errp)
 void object_unparent(Object *obj)
 {
     object_ref(obj);
-    if (obj->parent) {
-        object_property_del_child(obj->parent, obj, NULL);
-    }
     if (obj->class->unparent) {
         (obj->class->unparent)(obj);
     }
+    if (obj->parent) {
+        object_property_del_child(obj->parent, obj, NULL);
+    }
     object_unref(obj);
 }