optimize of #542 (initalizes $aroot)

php/elFinderVolumeLocalFileSystem.class.php

@@ -24,6 +24,13 @@ class elFinderVolumeLocalFileSystem extends elFinderVolumeDriver {
 	 **/
 	protected $archiveSize = 0;
 	
+	/**
+	 * Canonicalized absolute pathname of $root
+	 * 
+	 * @var strung
+	 */
+	protected $aroot;
+	
 	/**
 	 * Constructor
 	 * Extend options with required fields
@@ -264,6 +271,10 @@ class elFinderVolumeLocalFileSystem extends elFinderVolumeDriver {
 		}
 
 		//Verifies the given path is the root or is inside the root. Prevents directory traveral.
+		if (!$this->aroot) {
+			// for Inheritance class ( not calling parent::configure() )
+			$this->aroot = realpath($this->root);
+		}
 		if (!$this->_inpath(realpath($path), $this->aroot)) {
 			return $stat;
 		}