* keyboard.c (last_event_timestamp): Remove. For X selection and

* keyboard.c (last_event_timestamp): Remove.  For X selection and
GTK popup menus, it may be obtained from per-frame X display info.
(kbd_buffer_store_event_hold, kbd_buffer_get_event)
(process_special_events): Adjust users.
* keyboard.h (last_event_timestamp): Remove declaration.
* xmenu.c (xmenu_show, create_and_show_popup_menu): Lost last arg.
Use FRAME_DISPLAY_INFO (f)->last_user_time for gtk_menu_popup.
* menu.h (xmenu_show): Adjust prototype.
* menu.c (Fx_popup_menu): Adjust user.
* xselect.c (x_own_selection, x_get_foreign_selection)
(Fx_disown_selection_internal): Use dpyinfo->last_user_time.