RFR: 8192983: gc/g1/TestVerifyGCType.java might fail on loaded machines

[Stefan Johansson]

Hi,

Please review this test fix for:
https://bugs.openjdk.java.net/browse/JDK-8192983

Webrev:
http://cr.openjdk.java.net/~sjohanss/8192983/00/

Summary:
On big or loaded machines the tests was to fragile to always pass. Have 
added restrictions on the heap size and also made sure the test complete 
the concurrent cycle before the young GCs are triggered.

Testing:
* mach5 with 10 times repeat without any problems
* mach5 hotspot_gc test list with -Xcomp (failed in PIT) currently running

Thanks,
Stefan