8234397: add OS uptime information to os::print_os_info output

[Baesken, Matthias]

> 
> Hi Matthias,
> 
> I'd like to see the uptime information in hs_err files.
> 
> I, however, would rather like to see a more readable output like "OS uptime
> 10 days 3:10". I understand that's some more formatting effort but on the
> other hand you'd not need floating point calculations.
> 

Is  there  already some function available  that does the beautification  ?
Otherwise  the benefit is a bit small  just for the hs_err output .

> As for os_windows.cpp: Why don't you spend a
> os::win32::print_uptime_info(st); method to align with the other
> implementations?
> 

Ok why not ,  could do so  ...


Regards, Matthias