Automatically load plugins in folders inside the mu-plugins folder

autoloader.php

<?php
/**
 * Automatically loads plugins in folders
 *
 * @package mu-plugin-autoloader
 */

$dirs = array_filter( glob( WPMU_PLUGIN_DIR . '/*' ), 'is_dir' );
foreach ( $dirs as $dirpath ) {
	$regex = '/([^\/]+$)/';
	preg_match( $regex, $dirpath, $matches );
	$dirname = $matches[0];
	require_once WPMU_PLUGIN_DIR . "/$dirname/$dirname.php";
}