First: not sure if I selected the proper Component, I'm speaking about 
http://webcvs.freedesktop.org/xorg/lib/X11/

When I cross-compile this libary, e.g. with

/usr/src/sdk3001/tmp/work/x11-7.0+20060309-r0/X11/configure
--build=i686-linux --host=arm-linux --target=arm-linux --prefix=/usr
--exec_prefix=/usr --bindir=/usr/bin --sbindir=/usr/sbin
--libexecdir=/usr/libexec --datadir=/usr/share --sysconfdir=/etc
--sharedstatedir=/usr/com --localstatedir=/var --libdir=/usr/lib
--includedir=/usr/include --oldincludedir=/usr/include
--infodir=/usr/share/info --mandir=/usr/share/man --disable-xkb
--disable-xf86bigfont --enable-malloc0returnsnull

then in src/util the program "makekeys" is compiled with the cross-compiler 
for my ARM device, not with the host compiler.