Declare the `$submenu_file` global to avoid a notice generated by passing it as a parameter to the `submenu_file` hook, introduced in [34722].

Fixes #24531.

Built from https://develop.svn.wordpress.org/trunk@34724


git-svn-id: http://core.svn.wordpress.org/trunk@34688 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/menu-header.php

@@ -23,7 +23,7 @@ $self = preg_replace('|^.*/mu-plugins/|i', '', $self);
  * @global array  $submenu
  * @global string $parent_file
  */
-global $menu, $submenu, $parent_file;
+global $menu, $submenu, $parent_file, $submenu_file;
 
 /**
  * Filter the parent file of an admin menu sub-menu item.

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.4-alpha-34723';
+$wp_version = '4.4-alpha-34724';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.