Include config.h

Include config.h
[HAVE_XFT2]: Include <X11/Xft/Xft.h>.
(GCInfo) [HAVE_XFT2]: New member xft_color_fore, xft_color_back.
(MWDevice) [HAVE_XFT2]: New member xft_draw.
(FRAME_CMAP, FRAME_VISUAL): New macros.
(free_device) [HAVE_XFT2]: Destroy device->xft_draw.
(xfont_driver): Make it static.
(mwin__open_device) [HAVE_XFT2]: Setup device->xft_draw.
(mwin__realize_face) [HAVE_XFT2]: Setup info->xft_color_fore and
info->xft_color_back.
(MXftFontInfo) [HAVE_XFT2]: New type.
(mwin__xft_close) [HAVE_XFT2]: New function.
(mwin__xft_open) [HAVE_XFT2]: New function.
(mwin__xft_get_metric) [HAVE_XFT2]: New function.
(mwin__xft_render) [HAVE_XFT2]: New function.