RFR: 8255964: Add jcmd Thread.print to jtreg timeout handler

[Nils Eliasson]

This patch adds jcmd Thread.print to the jtreg timeout handler.

Please review.

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Commit messages:
 - Add jcmd thread.print to timeout handler

Changes: https://git.openjdk.java.net/jdk/pull/1080/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1080&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8255964
  Stats: 3 lines in 1 file changed: 3 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1080.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1080/head:pull/1080

PR: https://git.openjdk.java.net/jdk/pull/1080