Win32: call dnd exit when finalizing the display

Since we init dnd when opening the display, call the corresponding
exit function (which is unused at the moment) when finalizing the
display.

gdk/win32/gdkdisplay-win32.c

@@ -736,6 +736,7 @@ gdk_win32_display_finalize (GObject *object)
   GdkWin32Display *display_win32 = GDK_WIN32_DISPLAY (object);
 
   _gdk_win32_display_finalize_cursors (display_win32);
+  _gdk_win32_dnd_exit ();
 
   G_OBJECT_CLASS (gdk_win32_display_parent_class)->finalize (object);
 }