[gtk+] Drop an unused enum value

[Matthias Clasen <matthiasc src gnome org>]

commit 12e4f4256d7e23a2a9caaa5e2a76774f2b5a5adf
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Jan 1 13:27:56 2018 -0500

    Drop an unused enum value
    
    We haven't had a GtkWindow::frame-event since the
    linux-fb backends demise.

 gtk/gtkwindow.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkwindow.c b/gtk/gtkwindow.c
index 1f31437..0553e6b 100644
--- a/gtk/gtkwindow.c
+++ b/gtk/gtkwindow.c
@@ -287,7 +287,6 @@ static const char *dnd_dest_targets [] = {
 
 enum {
   SET_FOCUS,
-  FRAME_EVENT,
   ACTIVATE_FOCUS,
   ACTIVATE_DEFAULT,
   KEYS_CHANGED,