[libstdc++-v3] Remove std::construct and std::destroy

[Benjamin Kosnik]

> I was of the opinion that getting nonstandard names out of std:: as soon
> as possible would be a good thing, because there would be less opportunity
> for people to adopt their use (vis. the fd constructor in iostreams), but it's
> not a strident opinion.

Yeah I think this too.

> I have a similar patch in the pipe to remove some additional HP names that
> are not a part of the standard.  While I won't suggest this next patch go on the
> branch, I would like some opinion as to whether the nonstandard functions should
> be removed entirely (definition and all), have their definitions remain in the
> library but be unused by the library itself, or have their definitions moved
> into a backwards header.

Removed entirely.

-benjamin