[12u] 8220546: Shenandoah Reports timing details for weak root processing

[Roman Kennke]

Sorry, this somehow went under my radar. Patch looks good!

Thanks,
Roman


> Please review this 12u backport.
> 
> The patch did not apply cleanly, as string table is not processed by 
> WeakProcessor in 12u.
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8220546
> Original patch: http://hg.openjdk.java.net/jdk/jdk/rev/8b61a38be0c5
> Original review: 
> https://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2019-March/025070.html 
> 
> 
> JDK12u webrev: http://cr.openjdk.java.net/~zgu/JDK-8220546_12u/webrev.00/
> 
> Test:
>    hotspot_gc_shenandoah on Linux 64.
> 
> Thanks,
> 
> -Zhengyu
>