hg: zgc/zgc: ZGC: Add support for CollectedHeap::get_safepoint_workers()

[per.liden at oracle.com]

Changeset: 0a2feb9e2974
Author:    pliden
Date:      2018-05-08 13:48 +0200
URL:       http://hg.openjdk.java.net/zgc/zgc/rev/0a2feb9e2974

ZGC: Add support for CollectedHeap::get_safepoint_workers()

! src/hotspot/share/gc/z/zCollectedHeap.cpp
! src/hotspot/share/gc/z/zCollectedHeap.hpp
+ src/hotspot/share/gc/z/zRuntimeWorkers.cpp
+ src/hotspot/share/gc/z/zRuntimeWorkers.hpp