RFR(XXS) 8224508: Shenandoah: Need to update thread roots in final mark for piggyback ref update cycle

[Aleksey Shipilev]

On 5/21/19 10:50 PM, Zhengyu Gu wrote:
> The thread roots may still contain forwarded oops.
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8224508
> Webrev: http://cr.openjdk.java.net/~zgu/JDK-8224508/webrev.00/

Looks okay. Indent is not correct at L1509 here, please fix before pushing.

1508     if (has_forwarded_objects()) {
1509     // Degen may be caused by failed evacuation of roots
1510       if (is_degenerated_gc_in_progress()) {

-Aleksey