Take account of periodic fringe bitmap's dependency on y-position in redrawing.

Take account of periodic fringe bitmap's dependency on y-position in redrawing.

* dispextern.h (struct glyph_row): New member fringe_bitmap_periodic_p.

* dispnew.c (shift_glyph_matrix, scrolling_window): Mark scrolled row
for fringe update if it has periodic bitmap.
(row_equal_p): Also compare left_fringe_offset,	right_fringe_offset,
and fringe_bitmap_periodic_p.

* fringe.c (get_fringe_bitmap_data): New function.
(draw_fringe_bitmap_1, update_window_fringes): Use it.
(update_window_fringes): Record periodicity of fringe bitmap in glyph
row.  Mark glyph row for fringe update if periodicity changed.

* xdisp.c (try_window_reusing_current_matrix): Don't mark scrolled row
for fringe update unless it has periodic bitmap.