RFR: 8016331: Minor issues in event tracing metadata

[Erik Gahlin]

Hi,

Could I have a review of these small metadata changes for event tracing, 
most importantly the split of the ParallelScavangeHeapSummary event name..

http://cr.openjdk.java.net/~mgronlun/8016331/webrev01/

Thanks in advance
Erik