container: don't leak container reference

object_property_add_child() references the child, unref it after to
avoid ref leaks.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

qom/container.c

@@ -40,6 +40,7 @@ Object *container_get(Object *root, const char *path)
         if (!child) {
             child = object_new("container");
             object_property_add_child(obj, parts[i], child, NULL);
+            object_unref(child);
         }
     }