Finish work on cursor motion in continuation lines.

Finish work on cursor motion in continuation lines.

 xdisp.c (set_cursor_from_row): Don't miss a candidate row whose
 glyph->charpos is an exact match for point.
 (try_cursor_movement): Don't give up if rows are bidi-reordered
 and point moved backwards.  Instead, back up to the row that is
 not a continuation line.