msvcrt: Fix inconsistent rounding behaviour for sprintf and add tests.

[Piotr Caban]

On 01/26/15 12:29, YongHao Hu wrote:
> +            if(flags.Precision >= 0 && toupper(flags.Format)!='G') {
> +                temp = pow(10, flags.Precision);
> +                val  = round(val * temp) / temp;
> +            }
This is not correct, val may loose to much precision. Also temp can 
become INF (in your patch temp is int but I guess it's a mistake). I'm 
afraid that in order to fix this bug you'll need to stop using glibcs 
sprintf in wine's printf implementation.

Your patch to msvcp tests depends on this patch. Please send patches 
that depend on each other in series.

Thanks,
Piotr