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/class-wp-plugins-list-table.php

@@ -219,7 +219,7 @@ class WP_Plugins_List_Table extends WP_List_Table {
 	 * @return boolean
 	 */
 	public function _search_callback( $plugin ) {
-		static $term;
+		static $term = null;
 		if ( is_null( $term ) )
 			$term = wp_unslash( $_REQUEST['s'] );