more non-useless destructors desired

[Paolo Carlini]

Hi,
> Is there some reason why these should not have explicit destructors too?  Is it too late to add them due to ABI issues?
>   
first blush, I believe this change could be doable, because the
destructors already exist and are exported by the library anyway, only
as "W" instead of "T". Did you experiment already with actually
declaring / defining such destructors in stdexcept / stdexcept.cc?

Paolo.