ox-ascii: Fix TOC keyword

* lisp/ox-ascii.el (org-ascii--build-toc): Fix TOC keyword.

Reported-by: Rasmus <rasmus@gmx.us>
<http://permalink.gmane.org/gmane.emacs.orgmode/95843>

lisp/ox-ascii.el

@@ -781,7 +781,7 @@ contents according to the current headline."
 	    (or (not (plist-get info :with-tags))
 		(eq (plist-get info :with-tags) 'not-in-toc))
 	    'toc))))
-      (org-export-collect-headlines info n keyword) "\n"))))
+      (org-export-collect-headlines info n (and local keyword)) "\n"))))
 
 (defun org-ascii--list-listings (keyword info)
   "Return a list of listings.