RFR: 8303972: TestLocOffsetFromZip64EF could use a sparse file

[Eirik Bjorsnos]

Please review this PR which brings the currenly problem-listed test TestLocOffsetFromZip64EF back to life.

By using a sparse ZIP file instead of calling out to the `zip` command line, we can speed up the test (from 50s to 3s on my Macbook Pro), save 4GB disk space during builds and remove a dependency on the `zip` command in OS/distros.

To get an idea on how the new test performs on file systems which do not support sparse files, I also ran the using a disk image in MacOS with a non-spase file system. The test completed in 14 seconds.

Seee [JDK-8301183](https://bugs.openjdk.org/browse/JDK-8301183) for details on the problem-listing.

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Commit messages:
 - Remove accidentally introduced blank line
 - Merge branch 'master' into loc-offset-zip64-sparse
 - Rewrite TestLocOffsetFromZip64EF to create ZIP file using sparse ZipOutputStream instead of calling out to the ZIP command line

Changes: https://git.openjdk.org/jdk/pull/12979/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12979&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8303972
  Stats: 120 lines in 2 files changed: 20 ins; 56 del; 44 mod
  Patch: https://git.openjdk.org/jdk/pull/12979.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12979/head:pull/12979

PR: https://git.openjdk.org/jdk/pull/12979