Uninstallation of sys-devel/gcc[gcj] leaves broken symlink /usr/lib/pkgconfig/libgcj-${PV:0:3}.pc pointing to uninstalled libgcj-${PV}.pc. toolchain_pkg_postrm() calls gcc-config, so this bug probably should be fixed in sys-devel/gcc-config.
http://git.overlays.gentoo.org/gitweb/?p=proj/gcc-config.git;a=commitdiff;h=12a60e3fea8fe751f26d3153fbd940fad085038f