[RFC] PR 6015: number formatting is not mt-safe

[Paolo Carlini]

Hi all,

first blush (I'm not a MT expert) this PR seems sound. The current 
__convert_from_v has the following structure (which may be found also 
described on some glibc guidelines): save-current-locale; setlocale "C"; 
sprintf; setlocale back .

Indeed this seems /not/ MT safe.

OTOH, I think the current standard is completely silent about MT issues.

What do you all think? Is this a pure QoI issue? Is there something we 
can do about it?

Thanks,
Paolo.