Remaining host configuration fragments

[DJ Delorie]

> Sounds like a good idea to me.  You meant include/filenames.h, right?

Yeah, that one.

> I am trying to push a general principle that we should actively prune
> obsolete configurations rather than leave the code around to rot
> slowly and confuse people trying to do maintenance.

I think we should adopt something like gdb's policy - obsoletions
should be publically announced well in advance, noted in release X,
deprecated in release X+1, and removed in release X+2.

Otherwise, you risk obsoleting a platform that has a silent but
non-zero user base.