RFR [9] 8147543: Remove sun.misc.ManagedLocalsThread

[Chris Hegarty]

Another remaining JEP 260 task that can now be resolved ( remove a
non-Critical API from sun.misc ).

With all the subtasks of 8147543 [1] complete, i.e. all the dependencies on
ManagedLocalsThread have been removed, it is time to remove the type
itself ( its functionality has been superseded by the new Thread constructor
[2] ).

The changes are trivial:

  $ hr rm src/jdk.unsupported/share/classes/sun/misc/ManagedLocalsThread.java

-Chris.

[1] https://bugs.openjdk.java.net/browse/JDK-8147543
[2] https://bugs.openjdk.java.net/browse/JDK-8056152