Fix bug on mass mailling unsubsscribe fonctionnality

htdocs/public/emailing/mailing-unsubscribe.php

@@ -29,7 +29,7 @@ define("NOLOGIN",1);		// This means this output page does not require to be logg
 define("NOCSRFCHECK",1);	// We accept to go on this page from external web site.
 
 require '../../main.inc.php';
-require_once DOL_DOCUMENT_ROOT.'/lib/company.lib.php';
+dol_include_once('/core/lib/company.lib.php');
 
 global $user, $conf, $langs;