RFR [9] 8146736: Move sun.misc performance counters to jdk.internal.perf

[Chris Hegarty]

In preparation for JEP 260, the performance counters can be moved out of
sun.misc and located somewhere more appropriate, like jdk.internal.perf.

http://cr.openjdk.java.net/~chegar/8146736/

Mandy asked whether this change should go through jdk9/hs-rt or jdk9/dev,
I see no strong reason why is should go through hs-rt, so propose to go through
jdk9/dev, unless there are objections. The hotspot changes are minor.

Note: the use of cleaner in Perf will be replaced with the proposed CleanerFactory
when it is added.

-Chris.