hg: jdk/sandbox: 8243478: Shenandoah: avoid implicit worker_id = 0

[chris.hegarty at oracle.com]

Changeset: cfc5b66e39c8
Author:    zgu
Date:      2020-04-23 10:14 -0400
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/cfc5b66e39c8

8243478: Shenandoah: avoid implicit worker_id = 0
Reviewed-by: shade

! src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp
! src/hotspot/share/gc/shenandoah/shenandoahRootProcessor.hpp