[RFA/Patch] One more for libstdc++/28080

[Benjamin Kosnik]

> in order to make more substantive progress (really, probably my last one 
> for a while), I have in testing another batch of changes which start 
> actually reducing noticeably the size of the pre-proprocessed <memory> 
> (as requested in the original PR), all the containers, <algorithm>. The 
> idea is that normally (outside debug mode) we don't want for such 
> facilities to end up including <iosfwd> (and therefore <bits/gthr.h>) 
> which is remarkably big and has no actual uses in the implementation. If 
> we agree about that, 

I agree about this.

> then I would commit as a preparatory step the 
> below, say tomorrow evening, and then real soon will post the real patch 
> for final review. (Note that we are already including explicitely 
> <pthread.h> in many other tests, as should be always the case, in my 
> opinion).

Scanning through the testsuite, I do see that pthread.h is included in a 
lot of other places directly. So, I'm in agreement.

best,
benjamin