Add @static* annotations where they are missing.

Initialize all static vars that are not, most to `null`.

See #32444.


git-svn-id: https://develop.svn.wordpress.org/trunk@32650 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/includes/widgets.php

@@ -104,6 +104,8 @@ function wp_list_widget_controls( $sidebar, $sidebar_name = '' ) {
  *
  * @global array $wp_registered_widgets
  *
+ * @staticvar int $i
+ *
  * @param array $params
  * @return array
  */