RFR 9: 8078099 : (process) ProcessHandle should uniquely identify processes

[Roger Riggs]

Please review changes to ProcessHandle implementation to uniquely identify
processes based on the start time provided by the OS. It addresses the issue
of PID reuse.
This is the implementation of the ProcessHandle.equals() spec change in
    8129344 : (process) ProcessHandle instances should define equals 
and be value-based

Webrev:
  http://cr.openjdk.java.net/~rriggs/webrev-starttime-8078099/

Issue:
   https://bugs.openjdk.java.net/browse/JDK-8078099

Thanks, Roger