hg: shenandoah/jdk8u/hotspot: Cherry-pick/synchronize JDK-8180175 and JDK-8180599

[roman at kennke.org]

Changeset: 0d7228ed1443
Author:    rkennke
Date:      2017-05-22 11:32 +0200
URL:       http://hg.openjdk.java.net/shenandoah/jdk8u/hotspot/rev/0d7228ed1443

Cherry-pick/synchronize JDK-8180175 and JDK-8180599

! src/share/vm/gc_implementation/shenandoah/shenandoahRootProcessor.cpp
! src/share/vm/runtime/synchronizer.cpp
! src/share/vm/runtime/synchronizer.hpp
! src/share/vm/runtime/thread.cpp