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

[Jason Merrill]

>>>>> "Benjamin" == Benjamin Kosnik <bkoz@redhat.com> writes:

> I disagree. This is why we have the backward include directory. I think 
> code that's not in the standard and from the original HP implementation 
> should either be removed, or put into backward. 

The HP implementation was a de facto standard; people wrote code against
it.  In general, I consider breaking previously working code undesirable.
Sometimes it's unavoidable, but I think folks have been too cavalier about
tossing anything that's not in the standard without regard for usability.

I am in favor of deprecating this stuff, giving people a warning that they
really ought to change their code.  But I'm against breaking it with no
explanation.  If a function just disappears in a dot release, people are
liable to be confused, and submit bug reports about it.  Better, IMO, to
complain at them specifically about obsolete usage and then DTRT.

> I think the goal should be to have standards-conformant headers, and 
> older/deprecated headers available by request.

I'm amenable to this if the only thing a user needs to do is add something
to CXXFLAGS.

Jason