RFR (S): 8227442: Make young_index_in_cset zero-based

[Kim Barrett]

> On Aug 19, 2019, at 9:46 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
> http://cr.openjdk.java.net/~tschatzl/8227442/webrev.0_to_1/ (diff)
> http://cr.openjdk.java.net/~tschatzl/8227442/webrev.1/ (full)
> 
> Passes hs-tier1-3
> 
> Thanks,
>  Thomas

Looks good.