Fix quoting in org-agenda-with-point-at-orig-entry.

* org-agenda.el (org-agenda-with-point-at-orig-entry): Small
bugfix.

TINYCHANGE

lisp/org-agenda.el

@@ -1742,7 +1742,7 @@ in that string.  If STRING is nil, it will be fetched from the beginning
 of the current line."
   (org-with-gensyms (marker)
     `(let ((,marker (get-text-property (if string 0 (point-at-bol))
-				       'org-hd-marker string)))
+				       'org-hd-marker ,string)))
        (with-current-buffer (marker-buffer ,marker)
 	 (save-excursion
 	   (goto-char ,marker)