hg: shenandoah/jdk: Replace risky SBS::need_update_refs_barrier with straightforward check

[ashipile at redhat.com]

Changeset: 987f6f3b653a
Author:    shade
Date:      2018-06-18 18:31 +0200
URL:       http://hg.openjdk.java.net/shenandoah/jdk/rev/987f6f3b653a

Replace risky SBS::need_update_refs_barrier with straightforward check

! src/hotspot/share/gc/shenandoah/heuristics/shenandoahPartialHeuristics.cpp
! src/hotspot/share/gc/shenandoah/heuristics/shenandoahPartialHeuristics.hpp
! src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.cpp
! src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.hpp
! src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.inline.hpp
! src/hotspot/share/gc/shenandoah/shenandoahHeuristics.cpp
! src/hotspot/share/gc/shenandoah/shenandoahHeuristics.hpp