RFR: Backport of 8062537: [TESTBUG] Conflicting GC combinations in hotspot tests

[Andrey Zakharov]

Hi, team.
This is review for backport of JDK-8062537, we need because there is no 
two tests in jdk8 and there are no plans to backport it.
test/gc/defnew/HeapChangeLogging.java
test/gc/parallelScavenge/TestDynShrinkHeap.java

Nothing changed above this.
Bug:
https://bugs.openjdk.java.net/browse/JDK-8076102
webrev:
http://cr.openjdk.java.net/~azakharov/8076102/

Thanks.