RFR (M) 8135154: Move cards scanned and surviving young words aggregation to G1ParScanThreadStateSet

[Mikael Gerdin]

Hi all,

Here is the follow up change to 8135152 which moves some stats into the 
par scan thread state set.

Both cards scanned and surviving young words are per-collection values, 
they are cleared after a collection ends and it does not make any sense 
to have them being members of G1RemSet and G1CollectedHeap respectively.

I've split up the change into two webrevs, one for cards scanned:
http://cr.openjdk.java.net/~mgerdin/8135154_1/webrev.0
and one for surviving young words:
http://cr.openjdk.java.net/~mgerdin/8135154_2/webrev.0
I plan to push both as a single change, though.

Full webrev: http://cr.openjdk.java.net/~mgerdin/8135154/webrev.0
Bug: https://bugs.openjdk.java.net/browse/JDK-8135154

Testing: JPRT

/Mikael