[gtkmm] Revert "Gtk::Border: Fix the build now that GtkBorder is a just a typedef."

[Murray Cumming <murrayc src gnome org>]

commit 13c7b1f78f1dfa9dfc3fad6b43ff9aaf975e3f6c
Author: Murray Cumming <murrayc murrayc com>
Date:   Thu Dec 17 20:39:04 2015 +0100

    Revert "Gtk::Border: Fix the build now that GtkBorder is a just a typedef."
    
    This reverts commit 5e6b1912b0ed627dccb16b2cf00547cfeeb7654f.
    because the GTK+ change was reverted.

 gtk/src/border.hg |    6 ------
 1 files changed, 0 insertions(+), 6 deletions(-)
---
diff --git a/gtk/src/border.hg b/gtk/src/border.hg
index ad5064a..1940cb6 100644
--- a/gtk/src/border.hg
+++ b/gtk/src/border.hg
@@ -19,11 +19,6 @@
 _DEFS(gtkmm,gtk)
 
 #include <glibmm/value.h>
-#include <gdk/gdk.h>
-
-#ifndef DOXYGEN_SHOULD_SKIP_THIS
-extern "C" { typedef GdkBorder GtkBorder; }
-#endif /* DOXYGEN_SHOULD_SKIP_THIS */
 
 namespace Gtk
 {
@@ -33,7 +28,6 @@ namespace Gtk
 class Border
 {
   _CLASS_BOXEDTYPE(Border, GtkBorder, gtk_border_new, gtk_border_copy, gtk_border_free)
-  _CUSTOM_STRUCT_PROTOTYPE
 public:
 
   /** Get the width of the left border.