[Bug libstdc++/68200] g++ 5.2 optimizes out pointer assignment in libstdc++ mt_allocator freelist destructor, causing crash at global-dtor time

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68200

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I would like to deprecate mt_allocator, I don't recommend using it.