Remove long-obsolete docs
Remove long-obsolete docs

There are no traces of GDK_USE_XFT, GXID_HOST or GXID_PORT in the
code anymore.
(cherry picked from commit 7652c2b3e066b4b68a8ac9fcc6093d13d1e35f66)

Unity-Technologies/gtk,Distrotech/gtk,Distrotech/gtk,johne53/MB3Gtk-2,johne53/MB3Gtk-2,Unity-Technologies/gtk,Unity-Technologies/gtk,johne53/MB3Gtk-2,Distrotech/gtk,johne53/MB3Gtk-2,Unity-Technologies/gtk,Distrotech/gtk,johne53/MB3Gtk-2,Distrotech/gtk,Unity-Technologies/gtk