Update phpseclib to version 0.3.9.

apps/files_external/lib/sftp.php

@@ -25,16 +25,8 @@ class SFTP extends \OC\Files\Storage\Common {
 	private static $tempFiles = array();
 
 	public function __construct($params) {
-		// The sftp:// scheme has to be manually registered via inclusion of
-		// the 'Net/SFTP/Stream.php' file which registers the Net_SFTP_Stream
-		// stream wrapper as a side effect.
-		// A slightly better way to register the stream wrapper is available
-		// since phpseclib 0.3.7 in the form of a static call to
-		// Net_SFTP_Stream::register() which will trigger autoloading if
-		// necessary.
-		// TODO: Call Net_SFTP_Stream::register() instead when phpseclib is
-		//       updated to 0.3.7 or higher.
-		require_once 'Net/SFTP/Stream.php';
+		// Register sftp://
+		\Net_SFTP_Stream::register();
 
 		$this->host = $params['host'];
 		$proto = strpos($this->host, '://');