ui/gtk: remove unused code

This code was last used before commit 2ec7870 "ui: convert
GTK and SDL1 frontends to keycodemapdb".

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Message-id: 20200516072014.7766-4-vr_qemu@t-online.de
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

ui/gtk.c

@@ -112,15 +112,6 @@
 # define VTE_CHECK_VERSION(a, b, c) 0
 #endif
 
-/* Some older mingw versions lack this constant or have
- * it conditionally defined */
-#ifdef _WIN32
-# ifndef MAPVK_VK_TO_VSC
-#  define MAPVK_VK_TO_VSC 0
-# endif
-#endif
-
-
 #define HOTKEY_MODIFIERS        (GDK_CONTROL_MASK | GDK_MOD1_MASK)
 
 static const guint16 *keycode_map;