It might be due to non-working visibility. It is not sometimes fully supported in cross compiling. Probably simply (native) rebuild of binutils and/or gcc-4.0 should suffice.I will see with Robert Millan if they have been rebuilt at least once natively.
According to timestamps in http://ftp.gnuab.org/debian/pool-kfreebsd-amd64/main/b/binutils http://ftp.gnuab.org/debian/pool-kfreebsd-amd64/main/g/gcc-4.0/ gcc-4.0 is built against older (may be non-native) binutils.
Could you, please, check configure log for "checking for GNUC visibility attribute... yes"
There is a "yes" in the config log, so this seems to be supported.
Can you try to force it to "no", and consequently #define G_GNUC_INTERNAL as empty ? Will it work ? Thanks Petr