Encapsulating internal APIs in JDK 9 (sun.misc.Unsafe, etc.)

[mark.reinhold at oracle.com]

FYI:

  http://mail.openjdk.java.net/pipermail/jigsaw-dev/2015-August/004433.html

(Please reply on jigsaw-dev rather than on jdk9-dev or core-libs-dev.)

- Mark