hg: shenandoah/jdk10: Move (Java)Thread::_gc_state to lower offset to optimize barrier fast-path encoding

[ashipile at redhat.com]

Changeset: d8b264d29c5f
Author:    shade
Date:      2018-06-13 12:52 +0200
URL:       http://hg.openjdk.java.net/shenandoah/jdk10/rev/d8b264d29c5f

Move (Java)Thread::_gc_state to lower offset to optimize barrier fast-path encoding

! src/hotspot/share/runtime/thread.cpp
! src/hotspot/share/runtime/thread.hpp