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

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