(split_font_name): Compute numeric value of

(split_font_name): Compute numeric value of
XLFD_AVGWIDTH.
(LFACE_AVGWIDTH): New macro.
(LFACEP): Use AREF.
(check_lface_attrs): Check LFACE_AVGWIDTH.
(lface_fully_specified_p): Don't check LFACE_AVGWIDTH.
(set_lface_from_font_name): Set LFACE_AVGWIDTH.
(merge_face_vectors): Check LFACE_AVGWIDTH.
(Finternal_make_lisp_face): Use AREF.
(xm_set_menu_resources_from_menu_face)
(xl_set_menu_resources_from_menu_face): Check LFACE_AVGWIDTH.
(Finternal_lisp_face_empty_p): Use AREF.
(lface_same_font_attributes_p): Compare LFACE_AVGWIDTH.
(better_font_p, exact_face_match_p): Add parameter AVGWIDTH.
Compare average widths..
(best_matching_font): Arrange for comparing average widths.