[gtkmm] ButtonBox: Remove unnecessary _IMPLEMENTS_INTERFACE().

[Murray Cumming <murrayc src gnome org>]

commit 3c3da7271cc48411c78e54b83220077ad1b9fced
Author: Murray Cumming <murrayc murrayc com>
Date:   Sat Aug 22 10:42:54 2015 +0200

    ButtonBox: Remove unnecessary _IMPLEMENTS_INTERFACE().
    
    The base class already implements (and derives from) Gtk::Orientable.

 gtk/src/buttonbox.hg |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)
---
diff --git a/gtk/src/buttonbox.hg b/gtk/src/buttonbox.hg
index c73055f..880e0f2 100644
--- a/gtk/src/buttonbox.hg
+++ b/gtk/src/buttonbox.hg
@@ -54,7 +54,6 @@ class ButtonBox
   : public Box
 {
   _CLASS_GTKOBJECT(ButtonBox,GtkButtonBox,GTK_BUTTON_BOX,Gtk::Box,GtkBox)
-  _IMPLEMENTS_INTERFACE(Orientable)
 public:
   //Note that we try to use the same defaul parameter value as the default property value.
   _WRAP_CTOR(ButtonBox(Orientation orientation = ORIENTATION_HORIZONTAL), gtk_button_box_new)