RFR: 8140393: Move WorkerDataArray to its own file

[Erik Helin]

Hi all,

this patch moves the class WorkerDataArray into its own file. While
moving to the code, I also refurbished it a bit. WorkerDataArray used
to cache the results for calls to max(), min(), sum() etc because it
might be expensive too loop over the array. However, the array we are
iterating over will at most be as big as the number of GC threads (it is
very rare to use more than 1000 GC threads). Performance runs shows no
regressions at all, so I prefer to go with the simpler code.

Enhancement:
https://bugs.openjdk.java.net/browse/JDK-8140393

Webrev:
http://cr.openjdk.java.net/~ehelin/8140393/webrev.00/

Testing:
- JPRT
- Perf Aurora for performance regressions

Thanks,
Erik