RFR: 8133553: Running with -XX:+UseParallelGC -XX:OldSize=30k crashes jvm

[David Lindholm]

Hi,

Please review this patch that prevents the jvm to crash (or assert) when 
run with an extremely small value for the -XX:OldSize flag and a 
collector that uses GenCollectorPolicy.

Bug: https://bugs.openjdk.java.net/browse/JDK-8133553
Webrev: http://cr.openjdk.java.net/~david/JDK-8133553/webrev.00/

Testing: Passed JPRT.


Thanks,
David