RFR: 8213918: DumpReason JFR event is not covered by test

[Erik Gahlin]

Hi,

Could I have a review of an added test for the DumpReason event.

The test only checks for the "Crash" reason, because "Out of memory" is 
very hard to trigger reliably.

I also removed flush events from EventNames.java and 
TestLookForUntestedEvents. java as they have been removed from the JVM. 
The "Flush" event still exists so it should be there.

Bug:
https://bugs.openjdk.java.net/browse/JDK-8213918

Webrev:
http://cr.openjdk.java.net/~egahlin/8213918/

Testing:
test/jdk/jdk/jfr/event/runtime/TestDumpReason.java 100 times
test/jdk/jdk/jfr/event/metadata/TestLookForUntestedEvents.java

Thanks
Erik