[RFR] 8064716: TestHumongousShrinkHeap.java can not be run with -XX:+ExplicitGCInvokesConcurrent

[Andrey Zakharov]

Hi, team. Excuse me for disturbing you, here is simple fix for subj.
I've added explicit -XX:-ExplicitGCInvokesConcurrent to invocations

Its fixes at least twu test bugs:
https://bugs.openjdk.java.net/browse/JDK-8062957
https://bugs.openjdk.java.net/browse/JDK-8064716

webrev:
http://cr.openjdk.java.net/~azakharov/8064716/webrev/


Thanks.