RFR (XS): 8252038: G1: Remove unused G1MarkStatsCache::_num_stats

[Kim Barrett]

> On Aug 19, 2020, at 2:34 PM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
> 
> Hi all,
> 
>  can I have reviews for this removal of the unused G1MarkStatsCache::_num_stats and follow-up cleanup?
> 
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8252038
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8252038/webrev
> Testing:
> local compilation
> 
> Thanks,
>  Thomas

Looks good.