https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123326
--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Note, libstdc++-v3 Makefile has LIBICONV = /usr/local/lib/libiconv.so -Wl,-rpath -Wl,/usr/local/lib and LTLIBICONV = -L/usr/local/lib -liconv -R/usr/local/lib after configure, but guess neither of those is something suitable for possible libstdc++.spec.
