[8] RFR: Shenandoah: add root statistics for string dedup table/queues

[Aleksey Shipilev]

This one:
 https://cr.openjdk.java.net/~shade/shenandoah/8u-strdedup-root-stats/webrev.02/

...also adds the 8u-specific strdedup-thread counter.

Still passes hotspot_gc_shenandoah.

-Aleksey

On 5/19/20 1:51 PM, Zhengyu Gu wrote:
> Good to me.
> 
> -Zhengyu
> 
> On 5/18/20 9:11 AM, Aleksey Shipilev wrote:
>> This is sh/jdk8-specific fix to add root statistics for string dedup table/queues. This would match
>> what sh/jdk11 and jdk/jdk are doing.
>>
>> Webrev:
>>   https://cr.openjdk.java.net/~shade/shenandoah/8u-strdedup-root-stats/webre