RFR 8019370: Sync j.u.c Fork/Join from 166 to tl

[Paul Sandoz]

Hi,

This webrev contains updates of java.util.concurrent Fork/Join, executors, and related classes from 166:

  http://cr.openjdk.java.net/~psandoz/tl/JDK-8019370-fork-join/webrev/

There are also various doc updates/fixes included.

Most of this code has been in the lambda repo for quite a while (the diff between 166 and lambda is much much smaller than the diff between tl and lambda). This webrev was derived from the lambda code base after first syncing lambda with associated files from 166.

Paul.