(setup_for_ellipsis, get_next_display_element):

(setup_for_ellipsis, get_next_display_element):
Set it->ellipsis_p to 1 or 0.
(display_line): Record whether row ends in mid-ellipsis.
(set_cursor_from_row): If ends in ellipsis. find start of it.
(cursor_row_p): If PT's at the end of the ellipsis the row
ends within, don't display cursor on this row.

(BUFFER_POS_REACHED_P): We haven't reached the specified
position if we're reading from something other than the buffer.