libstdc++/9828: Regression: Segmentation fault in num_put::put

[Benjamin Kosnik]

>> > >__locale_cache<num_put<char> >& __lc = use_cache<num_put<char> >
>> > 
>> > Like this.
>
>I don't see any need to have separate caches per facet.  Indexing it
>by character type seems simpler, faster, and sufficient.

True.

>I don't think that's necessary.  Unless I'm severely mistaken, all 
>uses of locale::_Impl that care about its size are in non-template
>code in the library proper. 

Check globals.cc. I'm pretty sure that the "C" locale::Impl data was exported
in the 3.2.x ABI (it no longer is, FYI.). Thus, I think what Jerry
proposed is reasonable, if the other way is not possible.

-benjamin