[Bug libquadmath/85440] libquadmath and quadmath.h do not exist on ppc64

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85440

--- Comment #12 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Or configure the big endian compiler with VSX by default, e.g.
--with-cpu=power8 or similar.