ABSPATH not working! Any idea why?

If you just need that class included, and your script is located in the plugin directory, like /wp-content/plugins/pluginName/script.php, then you can do:

require realpath('../../../wp-includes/class-phpass.php');

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)