[Bug libstdc++/68825] testsuite/experimental/memory/shared_ptr/cons/copy_ctor_neg.cc fails to compile on powerpc64

[wschmidt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68825

--- Comment #4 from Bill Schmidt <wschmidt at gcc dot gnu.org> ---
Thanks, Jonathan!