RFR [8027348] (process) Enhancement of handling async close of ProcessInputStream

[Ivan Gerasimov]

Hello all!

May I have a review for the improvement contributed by Martin Buchholz?
https://bugs.openjdk.java.net/browse/JDK-8027348

First, it the change performs the code cleanup, and second it makes the 
test much faster.
This should also help to resolve the issue with the current version of 
the test, which was reported to fail intermittently by timeout.
https://bugs.openjdk.java.net/browse/JDK-8028574

Here's the webrev with the change:
http://cr.openjdk.java.net/~igerasim/8027348/0/webrev/

Sincerely yours,
Ivan Gerasimov