RFR: 8295350: JFR: Add stop methods for recording streams

[Erik Gahlin]

Could I have a review of PR that adds stop() methods to RecordingStream and RemoteRecordingStream. Purpose is to provide better control of what is being recorded.

Testing: test/jdk/jdk/jfr

Thanks
Erik

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Commit messages:
 - Set stream end for parser barrier
 - Initial

Changes: https://git.openjdk.org/jdk/pull/11337/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11337&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8295350
  Stats: 641 lines in 12 files changed: 636 ins; 2 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/11337.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11337/head:pull/11337

PR: https://git.openjdk.org/jdk/pull/11337