hg: jdk8u/jdk8u-dev/hotspot: 8065579: WB method to start G1 concurrent mark cycle should be introduced

[kevin.walls at oracle.com]

Changeset: 047a642c9729
Author:    kevinw
Date:      2015-12-02 13:58 +0530
URL:       http://hg.openjdk.java.net/jdk8u/jdk8u-dev/hotspot/rev/047a642c9729

8065579: WB method to start G1 concurrent mark cycle should be introduced
Summary: Add a WhiteBox callback to the VM to start a concurrent mark cycle in G1.
Reviewed-by: tschatzl, sjohanss
Contributed-by: Leonid Mesnik <leonid.mesnik at oracle.com>

! src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp
! src/share/vm/gc_implementation/g1/vm_operations_g1.cpp
! src/share/vm/gc_interface/gcCause.cpp
! src/share/vm/gc_interface/gcCause.hpp
! src/share/vm/prims/whitebox.cpp
+ test/gc/whitebox/TestConcMarkCycleWB.java
! test/testlibrary/whitebox/sun/hotspot/WhiteBox.java