hg: shenandoah/jdk10: Hint unused regions instead of uncommit them

[zgu at redhat.com]

Changeset: 46c3360b6623
Author:    zgu
Date:      2018-01-19 11:37 -0500
URL:       http://hg.openjdk.java.net/shenandoah/jdk10/rev/46c3360b6623

Hint unused regions instead of uncommit them

! src/hotspot/os/linux/os_linux.cpp
! src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp
! src/hotspot/share/gc/shenandoah/shenandoahHeap.hpp
! src/hotspot/share/gc/shenandoah/shenandoahHeapRegion.cpp
! src/hotspot/share/gc/shenandoah/shenandoahHeapRegion.hpp
! src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp
! src/hotspot/share/runtime/os.cpp
! src/hotspot/share/runtime/os.hpp
! test/hotspot/jtreg/gc/shenandoah/acceptance/HeapUncommit.java