RFR 9: 8138566: (Process) java.lang.Process.allChildren specification clarification

[Roger Riggs]

Please review and comment on 3 clarifications to ProcessHandle and Process.

Webrev:
http://cr.openjdk.java.net/~rriggs/webrev-process-clarify-8138566/

8138566: (Process) java.lang.Process.allChildren specification clarification
    - Rename the allChildren() method to descendants() - it is more 
descriptive and
       less easily confused with the children method.
    - The risk of renaming is method is minimal since it has been only 
available for a short time.

8140213: Process/ProcessHandle.onExit() spec need to be improved
    - The timing of the completion of the CompletableFuture was too 
tightly specified.
       With the isAlive method, it is possible to observe that the 
process has terminated
       before the CF is completed.  The CF is completed sometime after 
the process terminates.

8140250: (process) Process.info description is inaccurate
   - The specification of the Process/ProcessHandle.info() method did 
not match
      the implementation.  On an OS (Windows) some information is 
available about
      the process after it is no longer alive.

Thanks, Roger