[v3] possible backwards include removal

[Paolo Carlini]

Benjamin Kosnik wrote:

>These seem like likely candidates to me. None of these are expected per
>the standard. They've been warned as deprecated for the last four years.
>
>Let's ditch 'em.
>  
>
Of course, I agree with the idea, in principle. But why we are keeping
only *part* of the headers?
I think this is confusing. I vote for either removing everything or
nothing: and the possible rationale for the former option are exactly
those two that you mentioned above.

Paolo.