https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65670
--- Comment #3 from Matthias Klose <doko at gcc dot gnu.org> --- at least on powerpc64le this looks like a versioning issue. in 4.9 these were versioned @CXXABI_1.3.5, now in 5, they are versioned @GLIBCXX_3.4.15.
