[Bug libffi/48944] build error: "libffi has not been ported to avr-unknown-none."

[gjl at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48944

--- Comment #5 from Georg-Johann Lay <gjl at gcc dot gnu.org> 2011-05-11 12:23:00 UTC ---
I followed the recommendations in "Optimize disk usage" of

http://gcc.gnu.org/wiki/SvnSetup

and applied it to the following directories:

libada gnattools gcc/ada gcc/testsuite/ada
libstdc++-v3 libjava libgfortran libgo
gcc/java gcc/go

So the new configure setup don't support mapping non-needed subdirs to emptydir
as the previous configure.

After adding 

libffi boehm-gc zlib

the build passes without errors, but the host zlib then is not build (configure
adds --with-system-zlib to HOST_CONFIGARGS).

Is there a list of compatible directory sets that can be used according to
"Optimize disk usage"?