[gtkmm] Update a TODO comment

[Murray Cumming <murrayc src gnome org>]

commit 4e435a1088ea91930db023384d22a81f48f1931c
Author: Murray Cumming <murrayc murrayc com>
Date:   Wed Oct 9 10:59:02 2013 +0200

    Update a TODO comment

 gtk/src/linkbutton.hg |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)
---
diff --git a/gtk/src/linkbutton.hg b/gtk/src/linkbutton.hg
index 085cf28..8d9f6b2 100644
--- a/gtk/src/linkbutton.hg
+++ b/gtk/src/linkbutton.hg
@@ -24,7 +24,6 @@ _PINCLUDE(gtkmm/private/button_p.h)
 namespace Gtk
 {
 
-//TODO: Remove the mention of set_*_hook() when the C documentation has been fixed: 
https://bugzilla.gnome.org/show_bug.cgi?id=339745
 /** Create buttons bound to a URL.
  *
  * A Gtk::LinkButton is a Gtk::Button with a hyperlink, similar to the one