[ticket/13454] Remove unused variables

This is the first part of the changes. More to come.

PHPBB3-13454

phpBB/includes/ucp/ucp_pm_viewfolder.php

@@ -41,9 +41,6 @@ function view_folder($id, $mode, $folder_id, $folder)
 
 		$color_rows = array('marked', 'replied');
 
-		// only show the friend/foe color rows if the module is enabled
-		$zebra_enabled = false;
-
 		$_module = new p_master();
 		$_module->list_modules('ucp');
 		$_module->set_active('zebra');