Deprecate gdk_wayland_toplevel_unexport_handle

It doesn't do anything anymore, and is no longer
used internally. The replacement is
gdk_wayland_toplevel_drop_exported_handled().

gdk/wayland/gdktoplevel-wayland.c

@@ -2502,6 +2502,12 @@ export_handle_done (GObject      *source,
  * from another surface as transient for this one, see
  * [method@GdkWayland.WaylandToplevel.set_transient_for_exported].
  *
+ * Before 4.12, this API could not safely be used multiple times,
+ * since there was no reference counting for handles. Starting with
+ * 4.12, every call to this function obtains a new handle, and every
+ * call to [method@GdkWayland.WaylandToplevel.drop_exported_handle] drops
+ * just the handle that it is given.
+ *
  * Note that this API depends on an unstable Wayland protocol,
  * and thus may require changes in the future.
  *
@@ -2538,8 +2544,15 @@ gdk_wayland_toplevel_export_handle (GdkToplevel                *toplevel,
  * It is an error to call this function on a surface that
  * does not have a handle.
  *
+ * Since 4.12, this function does nothing. Use
+ * [method@GdkWayland.WaylandToplevel.drop_exported_handle] instead to drop a
+ * handle that was obtained with [method@GdkWayland.WaylandToplevel.export_handle].
+ *
  * Note that this API depends on an unstable Wayland protocol,
  * and thus may require changes in the future.
+ *
+ * Deprecated: 4.12: Use [method@GdkWayland.WaylandToplevel.drop_exported_handle]
+ *   instead, this function does nothing
  */
 void
 gdk_wayland_toplevel_unexport_handle (GdkToplevel *toplevel)

gdk/wayland/gdkwaylandtoplevel.h

@@ -52,7 +52,7 @@ gboolean                 gdk_wayland_toplevel_export_handle (GdkToplevel
                                                              gpointer                 user_data,
                                                              GDestroyNotify           destroy_func);
 
-GDK_AVAILABLE_IN_ALL
+GDK_DEPRECATED_IN_4_12_FOR(gdk_wayland_toplevel_drop_exported_handle)
 void                     gdk_wayland_toplevel_unexport_handle (GdkToplevel *toplevel);
 
 GDK_AVAILABLE_IN_4_12