(row_equal_p, update_window_line): Compare fringe bitmaps

(row_equal_p, update_window_line): Compare fringe bitmaps
instead of related indicator fields.
Compare exact_window_width_line_p and cursor_in_mouse_face_p indicators.
(direct_output_for_insert): Handle exact width lines like
contined lines.  Call update_window_fringes.
(update_window): Call update_window_fringes.
(scrolling_window): Don't skip desired rows with changed bitmaps.
Check if fringe bitmaps changes when assigning scrolled rows.