RFR: 8279821: JFR: Log warnings properly when loading a misconfigured .jfc file

[Erik Gahlin]

Hi,
Could I have a review of a fix that redirects a log warning from standard out to unified logging and dcmd output. For details, see bug.

Testing: jdk/jdk/jfr

Thanks
Erik

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Commit messages:
 - Initial

Changes: https://git.openjdk.java.net/jdk/pull/7024/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7024&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8279821
  Stats: 10 lines in 3 files changed: 1 ins; 0 del; 9 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7024.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7024/head:pull/7024

PR: https://git.openjdk.java.net/jdk/pull/7024