(mac_draw_rectangle, x_draw_glyph_string_foreground)

(mac_draw_rectangle, x_draw_glyph_string_foreground)
(x_draw_composite_glyph_string_foreground)
(x_draw_image_foreground): Undo previous changes.
(x_draw_hollow_cursor): Likewise.  Subtract 1 from the last
argument of mac_draw_rectangle.
(CG_SET_FILL_COLOR, CG_SET_STROKE_COLOR): New macros.
(mac_draw_string_common, mac_draw_image_string_cg): Use them.
(FRAME_CG_CONTEXT) [USE_CG_DRAWING]: New macro.
(mac_begin_cg_clip, mac_end_cg_clip, mac_prepare_for_quickdraw)
[USE_CG_DRAWING]: New functions.
(mac_draw_line, mac_erase_rectangle, mac_clear_window)
(mac_fill_rectangle, mac_draw_rectangle, mac_draw_string_common)
(mac_draw_image_string_cg) [USE_CG_DRAWING]: Add Quartz 2D drawing part.
(mac_draw_bitmap, mac_invert_rectangle, mac_draw_string_common)
(mac_copy_area, mac_scroll_area, x_scroll_bar_create)
(x_scroll_bar_remove, XTset_vertical_scroll_bar, x_set_window_size)
(XTread_socket) [USE_CG_DRAWING]: Call mac_prepare_for_quickdraw.