hg: jdk/sandbox: 8232594: Make the output of the JFR command duration more user friendly

[chris.hegarty at oracle.com]

Changeset: 43eee1237934
Author:    cito
Date:      2019-11-28 18:30 +0100
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/43eee1237934

8232594: Make the output of the JFR command duration more user friendly
Reviewed-by: egahlin, cito
Contributed-by: chiroito107 at gmail.com, erik.gahlin at oracle.com

! src/jdk.jfr/share/classes/jdk/jfr/internal/Utils.java
! src/jdk.jfr/share/classes/jdk/jfr/internal/tool/PrettyWriter.java
+ test/jdk/jdk/jfr/jvm/TestFormatDuration.java