implementation of std::thread::hardware_concurrency()

[Mike Stump]

On Nov 1, 2011, at 10:13 AM, Jonathan Wakely wrote:
>> I suspect on some systems, this would be a runtime value....  so, no fixed constant could ever work.
> 
> It's a constant for identifying the sysctl, not a constant for the
> number of processors e.g. (untested)

Ah, never mind, ignore me.