org-colview: Fix agenda columns with diary entries

* lisp/org-colview.el (org-agenda-columns): Do not treat diary entries
  as headlines.

Reported-by: "Éibhear" <eibhear.geo@gmail.com>
<http://permalink.gmane.org/gmane.emacs.orgmode/113282>

lisp/org-colview.el

@@ -1531,8 +1531,7 @@ PARAMS is a property list of parameters:
       (goto-char (point-min))
       (let (cache)
 	(while (not (eobp))
-	  (let ((m (or (org-get-at-bol 'org-hd-marker)
-		       (org-get-at-bol 'org-marker))))
+	  (let ((m (org-get-at-bol 'org-hd-marker)))
 	    (when m
 	      (push (cons (line-beginning-position)
 			  ;; `org-columns-current-fmt-compiled' is