[ticket/12352] Add legacy passwords driver for sha1 smf type passwords

PHPBB3-12352

phpBB/phpbb/passwords/driver/driver_interface.php

@@ -22,6 +22,13 @@ interface driver_interface
 	*/
 	public function is_supported();
 
+	/**
+	* Check if hash type is a legacy hash type
+	*
+	* @return bool		True if it's a legacy hash type, false if not
+	*/
+	public function is_legacy();
+
 	/**
 	* Returns the hash prefix
 	*