(next_element_from_ellipsis): Save face before selective

(next_element_from_ellipsis): Save face before selective
display in saved_face_id, and set face_before_selective_p.
(reseat_1): Reset face_before_selective_p.
(append_space, extend_face_to_end_of_line): If iterator's
face_before_selective_p is set, use the face from saved_face_id.
(extend_face_to_end_of_line): For tty frames, make sure to
use the right face id when producing spaces at the end of
the line.