(clip_changed): Variable deleted.

(clip_changed): Variable deleted.
(prepare_menu_bars): Don't look at clip_changed.
(redisplay): Don't set clip_changed.  Do set b's clip_changed.
(redisplay_window): Check clip_changed in current_buffer.
(mark_window_display_accurate): Clear clip_changed in the window's buffer.

(redisplay_window): Update individual window's mode line
if %c calls for an update.
(redisplay): Set update_mode_line for selected window only,
if it needs this because of %c.