RFR: jsr166 integration 2019-06

[Martin Buchholz]

https://cr.openjdk.java.net/~martin/webrevs/jdk/jsr166-integration/overview.html

Just another test timeout tweak:
8224024: java/util/concurrent/BlockingQueue/DrainToFails.java testBounded
fails intermittently
https://cr.openjdk.java.net/~martin/webrevs/jdk/jsr166-integration/DrainToFails/index.html
https://bugs.openjdk.java.net/browse/JDK-8224024

8220478: java/util/concurrent/ConcurrentHashMap/ToArray.java timed out
intermittently
https://cr.openjdk.java.net/~martin/webrevs/jdk/jsr166-integration/forkjoin/index.html
8223379: Clarify ForkJoinPool.getStealCount() javadoc
https://bugs.openjdk.java.net/browse/JDK-8220478

8223245: Miscellaneous changes imported from jsr166 CVS 2019-06
https://cr.openjdk.java.net/~martin/webrevs/jdk/jsr166-integration/miscellaneous/index.html
https://bugs.openjdk.java.net/browse/JDK-8223245