(mac_draw_image_string, mac_draw_image_string_16): Add

(mac_draw_image_string, mac_draw_image_string_16): Add
argument OVERSTRIKE_P.
(mac_draw_string_common, mac_draw_image_string_cg): Likewise.
Support overstrike.
(mac_draw_string, mac_draw_string_16): Remove functions.
(x_draw_glyph_string_foreground): Use overstrike when needed.
(x_draw_composite_glyph_string_foreground): Likewise.  Use
mac_draw_image_string_16 instead of mac_draw_string_16.
(mac_load_query_font): Rename from XLoadQueryFont.  Take argument F
instead of DPY.  All uses changed.  Don't save/restore font.