RFR (T): 8222105: Rename G1Policy::adaptive_young_list_length

[Kim Barrett]

> On Apr 8, 2019, at 5:14 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
> 
> Hi all,
> 
>  in the review for 8218668: Clean up evacuation of optional collection
> set Kim noted that the name for G1Policy::adaptive_young_list_length
> should be improved by adding a "use_" prefix to it.
> 
> This change does exactly that.
> 
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8222105
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8222105/webrev/
> Testing:
> local compilation
> 
> Thanks,
>  Thomas

Looks good, and trivial.