RFR (S): 8136679: JFR Event for adaptive IHOP

[Thomas Schatzl]

Hi all,

  can I have reviews for this change that adds a JFR event for adaptive
IHOP?

The change provides the same information as the IHOP related log
messages as JFR events.

CR:
https://bugs.openjdk.java.net/browse/JDK-8136679
Webrev:
http://cr.openjdk.java.net/~tschatzl/8136679/webrev/
Testing:
jprt, new (basic) jtreg test

Thanks,
  Thomas