Don't link libXft when using cairo

Don't link libXft when using cairo

* configure.ac: Check cairo early.  Don't try Xft if cairo is used.
* lwlib/lwlib-utils.h [USE_CAIRO]: Include cairo.h and fontconfig.h.
(XftFont, XftDraw, XftColor, XGlyphInfo) [USE_CAIRO]: New typedefs.
(XftFontOpenName, XftFontClose, XftDrawCreate, XftDrawDestroy)
(XftDrawRect, XftDrawStringUtf8, XftTextExtentsUtf8) [USE_CAIRO]: New macros.
(crxft_font_open_name, crxft_font_close, crxft_draw_create)
(crxft_draw_rect, crxft_draw_string, crxft_text_extents) [USE_CAIRO]: New
externs.
* lwlib/lwlib-utils.c [USE_CAIRO]: Include math.h, cairo-ft.h, and
cairo-xlib.h.
(crxft_font_open_name, crxft_font_close, crxft_draw_create)
(crxft_set_source_color, crxft_draw_rect, crxft_draw_string)
(crxft_text_extents) [USE_CAIRO]: New Xft compatibility functions.
* lwlib/xlwmenuP.h [USE_CAIRO]: Include lwlib-utils.h.
* lwlib/xlwmenu.c (display_menu_item) [USE_CAIRO]: Call
cairo_surface_mark_dirty and cairo_surface_flush.
* lwlib/lwlib-Xaw.c [USE_CAIRO]: Include stdlib.h and lwlib-utils.h.
(draw_text) [USE_CAIRO]: Call cairo_surface_flush.
* src/xsettings.c [USE_CAIRO]: Include fontconfig.h
(apply_xft_settings) [!HAVE_XFT]: Don't call XftDefaultSubstitute or
XftDefaultSet.
* lwlib/lwlib-Xaw.c:
* lwlib/lwlib-int.h:
* lwlib/xlwmenu.c:
* lwlib/xlwmenuP.h:
* src/xrdb.c:
* src/xsettings.c:
* src/xterm.c: Replace all #ifdef HAVE_XFT with #if defined USE_CAIRO ||
defined HAVE_XFT.
* src/xfns.c (x_default_font_parameter): Replace #ifdef HAVE_XFT with #if
defined	USE_CAIRO || defined HAVE_XFT.