Upgrade Visual studio 2017 15.8

- Upgrade to 15.8
- Add check on CGATS memory allocation (thanks to Quang Nguyen for
pointing out this)
cmsFloat64Number xpow10(int n)
{
    return pow(10, (cmsFloat64Number) n);
}

cmsFloat64Number xpow10(int n)
{
    return pow(10, (cmsFloat64Number) n);
}
