RFR: JDK-8134761 - Add PrintGCDetails for debugging JDK-8134523

[Eric Caspole]

Hi everybody,
I'd like to add +PrintGCDetails and +PrintHeapAtGC to a rarely-failing test:

  http://cr.openjdk.java.net/~ecaspole/JDK-8134761/00/webrev/

ER:
  https://bugs.openjdk.java.net/browse/JDK-8134761


This is to help debug a failure in a new humongous test, see the 
original bug:

  https://bugs.openjdk.java.net/browse/JDK-8134523

I do see the PrintGCDetails output in the .jtr file when run locally so 
I think JPRT will capture it as well.
Thanks,
Eric