Setup the font path to built-ins only.

x11-base/xorg-server/xorg-server-1.9.3-r9.ebuild

 # Copyright 1999-2010 Gentoo Foundation
 # Distributed under the terms of the GNU General Public License v2
 # $Header: /var/cvsroot/gentoo-x86/x11-base/xorg-server/xorg-server-1.9.2.ebuild,v 1.3 2010/12/19 13:07:34 ssuominen Exp $
 
 EAPI=3
 # They generate the configure.ac with wrong version of util-macros
 # see bug #339988
 XORG_EAUTORECONF="yes"
 inherit xorg-2 multilib versionator
 
@@ skipping 160 matching lines @@
                 $(use_enable opengl glx)
                 $(use_enable x86 xaa)
                 $(use_enable xorg)
                 $(use_enable nptl glx-tls)
                 $(use_enable udev config-udev)
                 $(use_with doc doxygen)
                 $(use_with doc xmlto)
                 --sysconfdir=/etc/X11
                 --localstatedir=/var
                 --enable-install-setuid
-                --with-fontrootdir=/usr/share/fonts
                 --with-xkb-output=/var/lib/xkb
                 --disable-config-hal
                 --without-dtrace
                 --without-fop
                 --with-sha1=libcrypto
                 --disable-xvmc
                 --disable-xdmcp
                 --disable-screensaver
                 --disable-xdm-auth-1
                 --disable-dbe
                 --disable-xinerama
                 --disable-dga
                 --disable-xace
                 --disable-config-dbus
                 --disable-config-hal
                 --disable-clientids
                 --disable-xf86vidmode
                 --disable-registry
                 --disable-xfake
                 --disable-dmx
                 --disable-xvfb
                 --disable-xnest
                 --enable-null-root-cursor
+                --with-default-font-path=built-ins
                 ${conf_opts}"
 
         # Things we may want to remove later:
         #       --disable-xaa (requires dropping all xaa drivers)
         #       --disable-xv (requires fixing the drivers)
         #       --disable-tcp-transport
         #       --disable-ipv6
         #       --disable-secure-rpc
 
         # Xorg-server requires includes from OS mesa which are not visible for
@@ skipping 107 matching lines @@
 }
 
 ensure_a_server_is_building() {
         for server in ${IUSE_SERVERS}; do
                 use ${server} && return;
         done
         eerror "You need to specify at least one server to build."
         eerror "Valid servers are: ${IUSE_SERVERS}."
         die "No servers were specified to build."
 }