hg: shenandoah/jdk10: Simplify and optimize ShenandoahHeap::requires_marking()

[roman at kennke.org]

Changeset: 2795496dbaf3
Author:    rkennke
Date:      2018-01-11 12:12 +0100
URL:       http://hg.openjdk.java.net/shenandoah/jdk10/rev/2795496dbaf3

Simplify and optimize ShenandoahHeap::requires_marking()

! src/hotspot/share/gc/shenandoah/shenandoahHeap.inline.hpp
! src/hotspot/share/gc/shenandoah/shenandoahPartialGC.cpp