RFR: 8256735: JFR: 'jfr' tool displays incorrect timestamps

[Erik Gahlin]

Hi,

Could I have a review that adds the date to jfr tool output. 

Testing: jdk/jdk/jfr + manual inspection

Thanks
Erik

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Commit messages:
 - Initial

Changes: https://git.openjdk.java.net/jdk/pull/5494/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5494&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8256735
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5494.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5494/head:pull/5494

PR: https://git.openjdk.java.net/jdk/pull/5494