org-odt.el: Fix handling of internal links
* lisp/org-odt.el (org-odt-format-org-link): Pay no heed to
whether the internal links destined for headlines provide a
description or not. In fact, the `org-store-link' and
`org-insert-link' create internal links which do have a
description.
This fixes an issue where internal links terminating at an
invisible target (that is bound to a headline) was badly
rendered. Refer following thread:
http://lists.gnu.org/archive/html/emacs-orgmode/2012-04/msg00757.html