Review request for JDK-8151660: Revert NativeBuffer.java to use jdk.internal.ref.Cleaner

[Mandy Chung]

http://cr.openjdk.java.net/~mchung/jdk9/webrevs/8151660/webrev.00/

This is to revert NativeBuffer.java change in JDK-8149925.  I can’t reliably reproduce the recursive initialization and this issue seems to be sensitive to the system configuration. JPRT build and tests are fine. I’m inclined to push this change to jdk9/dev to get tested.

Mandy