RFR: 8165955: TestFullGCCount test failed with CMS and -XX:+ExplicitGCInvokesConcurrent

[Michail Chernov]

Hi,

Could I have a reviews for this small change which excludes test run 
with CMS and -XX:+ExplicitGCInvokesConcurrent, please?

https://bugs.openjdk.java.net/browse/JDK-8165955
http://cr.openjdk.java.net/~mchernov/8165955/webrev.00/

Test fails because CMS with -XX:+ExplicitGCInvokesConcurrent causes to 
java's threads unlocking before CMSCollector::sweep() has been done. So 
the GC counters can be updated after test gets their value.

Thanks,
Michail