Backport request: JDK-8085823: [REDO] GCCause should distinguish jcmd GC.run from System.gc()

[Yasumasa Suenaga]

Hi all,

JDK-8072913 has been merged to jdk9, however, this change cannot apply to jdk8u
which is caused by JDK-8071908 and JDK-8079792.

I've uploaded webrev for this backport request.
Could you review it?

http://cr.openjdk.java.net/~ysuenaga/JDK-8085823/webrev.00/


Thanks,

Yasumasa