hg: shenandoah/jdk8u/hotspot: Make sure -verbose:gc, PrintGC, PrintGCDetails work consistently

[ashipile at redhat.com]

Changeset: e6b454424b51
Author:    shade
Date:      2017-09-07 19:22 +0200
URL:       http://hg.openjdk.java.net/shenandoah/jdk8u/hotspot/rev/e6b454424b51

Make sure -verbose:gc, PrintGC, PrintGCDetails work consistently

! src/share/vm/gc_implementation/shenandoah/shenandoahConcurrentThread.cpp
! src/share/vm/gc_implementation/shenandoah/shenandoahHeap.cpp
! src/share/vm/gc_implementation/shenandoah/shenandoahLogging.hpp
! src/share/vm/gc_implementation/shenandoah/shenandoahMarkCompact.cpp
! src/share/vm/gc_implementation/shenandoah/vm_operations_shenandoah.cpp
! src/share/vm/runtime/arguments.cpp
! test/gc/shenandoah/TestPeriodicGC.java
+ test/gc/shenandoah/options/TestVerboseGC.java