MDL-64240 mod_forum: Update word count to use current message length

Previously this used the length of the message stored in the database,
before scripts etc are cleaned to display the content. That resulted
in cases where the count would seem much larger than the message size.

mod/forum/lib.php

@@ -3523,7 +3523,7 @@ function forum_print_post($post, $discussion, $forum, &$cm, $course, $ownpost=fa
             $postcontent = highlight($highlight, $postcontent);
         }
         if (!empty($forum->displaywordcount)) {
-            $postcontent .= html_writer::tag('div', get_string('numwords', 'moodle', count_words($post->message)),
+            $postcontent .= html_writer::tag('div', get_string('numwords', 'moodle', count_words($postcontent)),
                 array('class'=>'post-word-count'));
         }
         $postcontent .= html_writer::tag('div', $attachedimages, array('class'=>'attachedimages'));