[Bug libstdc++/57350] std::align missing

[potswa at mac dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57350

--- Comment #5 from David Krauss <potswa at mac dot com> ---
Just re-reading now, std::size_t should be std::uintptr_t, but I don't see
anything else that could cause UB. The bitwise "negative" arithmetic should be
OK because it's all on unsigned values.

And if GNU style doesn't allow auto, those should just be uintptr_t or size_t
as appropriate.