[Rev 04] RFR: 6554: Support JFR in OpenJDK 8

[Marcus Hirt]

> This is for OpenJDK 8 implementations that have backported JFR, e.g. Azul's JDK. There is also a backport effort for OpenJDK 8 in general.

The pull request has been updated with 1 additional commit.

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Added commits:
 - 017555a4: Adding tests

Changes:
  - all: https://git.openjdk.java.net/jmc/pull/19/files
  - new: https://git.openjdk.java.net/jmc/pull/19/files/69898c6f..017555a4

Webrevs:
 - full: https://webrevs.openjdk.java.net/jmc/19/webrev.04
 - incr: https://webrevs.openjdk.java.net/jmc/19/webrev.03-04

  Stats: 29 lines in 1 file changed: 20 ins; 0 del; 9 mod
  Patch: https://git.openjdk.java.net/jmc/pull/19.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/19/head:pull/19

PR: https://git.openjdk.java.net/jmc/pull/19