If I understand toolchain.eclass correctly, include-fixed dir (generated by fixincludes) should not exist, cause all generated headers should have been removed during install. However, for some reason for gcc 4.3.0 it does exist and is not empty.
Minor correction. Of course, not all of those files should be removed, only the autogenerated ones.
should be fixed now ... fixed inc dir changed names on us http://sources.gentoo.org/eclass/toolchain.eclass?r1=1.351&r2=1.352