RFR: 8266936: Add a finalization JFR event [v2]

[Markus Grönlund]

> Greetings,
> 
> Object.finalize() was deprecated in JDK9. There is an ongoing effort to replace and mitigate Object.finalize() uses in the JDK libraries; please see https://bugs.openjdk.java.net/browse/JDK-8253568 for more information. 
> 
> We also like to assist users in replacing and mitigating uses in non-JDK code.
> 
> Hence, this changeset adds a periodic JFR event to help identify which classes are overriding Object.finalize().
> 
> Thanks
> Markus

Markus Grönlund has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 16 additional commits since the last revision:

 - merge
 - whitespace
 - update
 - update
 - whitespace
 - 8266936-alt: Add a finalization JFR event
 - shortcut calling Jfr::is_recording()
 - 8266936: Add a finalization JFR event
 - Code Source attribute for Finalizer event
 - whitespace
 - ... and 6 more: https://git.openjdk.java.net/jdk/compare/021c6513...d4d154e8

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/4731/files
  - new: https://git.openjdk.java.net/jdk/pull/4731/files/9a966f9f..d4d154e8

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=4731&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=4731&range=00-01

  Stats: 10639 lines in 412 files changed: 6366 ins; 2700 del; 1573 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4731.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4731/head:pull/4731

PR: https://git.openjdk.java.net/jdk/pull/4731