MDL-53702 mod_forum: Remove unused variables

mod/forum/lib.php

@@ -1823,8 +1823,6 @@ function forum_get_all_discussion_posts($discussionid, $sort, $tracking=false) {
     $params = array();
 
     if ($tracking) {
-        $now = time();
-        $cutoffdate = $now - ($CFG->forum_oldpostdays * 24 * 3600);
         $tr_sel  = ", fr.id AS postread";
         $tr_join = "LEFT JOIN {forum_read} fr ON (fr.postid = p.id AND fr.userid = ?)";
         $params[] = $USER->id;