Request for review JDK-8185591 guarantee(_byte_map[_guard_index] == last_card) failed: card table guard has been modified

[Kim Barrett]

> On Nov 22, 2017, at 3:28 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
> 
> https://www.intel.com/content/dam/www/public/us/en/documents/manual
> s/64-ia-32-architectures-optimization-manual.pdf , 3-13

Thanks for the cite.

Change looks good.