RFR (s): 8153755: Improve test: stress/gc/TestStressRSetCoarsening.java

[Dmitry Fazunenko]

Hello,

May I have a couple of reviews for a small change to the stress test:

1) change logging options (-XX:+PrintGC --> -Xlog:gc*)
2) Use WhiteBox API to obtain size of new Object[N] object


https://bugs.openjdk.java.net/browse/JDK-8153755
http://cr.openjdk.java.net/~dfazunen/8153755/webrev.00/

Testing: locally + RBT

Thanks,
Dima