RFR: jsr166 integration 2018-12

[Martin Buchholz]

Last jdk12 jsr166 integration.
https://cr.openjdk.java.net/~martin/webrevs/jdk/jsr166-integration/overview.html

8214559: Use {@systemProperty} for definitions of system properties
https://cr.openjdk.java.net/~martin/webrevs/jdk/jsr166-integration/systemProperty/index.html
https://bugs.openjdk.java.net/browse/JDK-8214559

8214427: probable bug in logic of ConcurrentHashMap.addCount()
https://cr.openjdk.java.net/~martin/webrevs/jdk/jsr166-integration/addCount/index.html
https://bugs.openjdk.java.net/browse/JDK-8214427

Still in limbo:
8203662: remove increment of modCount from ArrayList and Vector replaceAll()
https://cr.openjdk.java.net/~martin/webrevs/jdk/jsr166-integration/replaceAll/index.html
https://bugs.openjdk.java.net/browse/JDK-8203662

8214457: Miscellaneous changes imported from jsr166 CVS 2018-12
https://cr.openjdk.java.net/~martin/webrevs/jdk/jsr166-integration/miscellaneous/index.html
https://bugs.openjdk.java.net/browse/JDK-8214457