parent_path set to path not in hook_menu_default_menu_links causes menu link to not revert

Reproduce: Have a default menu link exported from features with a parent that is added via hook_menu (for example) and not hook_menu_default_menu_links.

Since this doesn't test if menu item is managed by a feature.

if (!empty($link['plid']) && $parent = menu_link_load($link['plid'])) {
  $link['parent_path'] = $parent['link_path'];
}

When menu_links_features_rebuild_ordered is reordering, it drops the menu item as both conditions always fail.

Patch tests and lets it catch the first if statement. Later, if the menu item exists, even if not managed by features, it sets the parent as features_menu_link_load doesn't care who made the menu link :)!.