Users: `$user_level` has been publicly-accessed on instances of `WP_User` since version 2.0, but is has never been declared.

See #37771.


git-svn-id: https://develop.svn.wordpress.org/trunk@38317 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-user.php

@@ -85,6 +85,13 @@ class WP_User {
 	 */
 	public $allcaps = array();
 
+	/**
+	 * @since 2.0.0
+	 * @access public
+	 * @var int
+	 */
+	public $user_level = 0;
+
 	/**
 	 * The filter context applied to user data fields.
 	 *