RFR: 8283520: JFR: Memory leak in dcmd_arena

[Markus Grönlund]

Greetings,

This changeset will address the memory leak in the dcmd_arena.

Testing: jdk_jfr

Thanks to @shipilev for reporting this issue.

Thanks
Markus

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Commit messages:
 - remove unused thread param
 - 8283520

Changes: https://git.openjdk.java.net/jdk/pull/8727/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8727&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8283520
  Stats: 29 lines in 3 files changed: 23 ins; 0 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8727.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8727/head:pull/8727

PR: https://git.openjdk.java.net/jdk/pull/8727