RFR: 8371978: tools/jar/ReproducibleJar.java fails on XFS

[SendaoYan]

Hi all,

Test tools/jar/ReproducibleJar.java fails when running on a file system that only supports to 2038(e.g. XFS).

Before this PR, test check if the input test time after "2038-01-19T03:14:07Z" and the extracted time created by jar is equal to "2038-01-19T03:14:07Z", then test will skip that check.

But the extraced time created by jar equal to "1970-01-01T00:00:00Z" actually. I think the extracted time set to unix epoch time is acceptable, so this PR fix the test make test check skip when the extracted time is unix epoch time.

Change has been verified locally on XFS file system and ext4 file system.

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Commit messages:
 - 8371978: ReproducibleJar.testValidSourceDate fails on some machines

Changes: https://git.openjdk.org/jdk/pull/28367/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28367&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8371978
  Stats: 11 lines in 1 file changed: 5 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/28367.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28367/head:pull/28367

PR: https://git.openjdk.org/jdk/pull/28367