RFR: 8303891: Zip64SizeTest could use a sparse file [v3]

[Eirik Bjorsnos]

> This PR suggests we use a sparse file when the Zip64SizeTest writes a ZIP file with a 5GB entry.
> 
> The size requirement of this test is known to cause problems in some builds, see [JDK-8259866](https://bugs.openjdk.org/browse/JDK-8259866)
> 
> Using a sparse file reduces the disk space requirements of running the test from 5GB to 12K and also reduces the runtime from ~35 seconds to ~3 seconds on my Macbook Pro.

Eirik Bjorsnos has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains six additional commits since the last revision:

 - Merge branch 'master' into zip64-size-test-sparse
 - Make test method public
 - Add a missing "when" in Javadocs for SparseOutputStream
 - Remove introduced blank line
 - Remove double whitespace
 - Rewrite Zip64SizeTest to write to a sparse file

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/12948/files
  - new: https://git.openjdk.org/jdk/pull/12948/files/d3a8d785..883f543f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12948&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12948&range=01-02

  Stats: 53410 lines in 360 files changed: 53053 ins; 202 del; 155 mod
  Patch: https://git.openjdk.org/jdk/pull/12948.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12948/head:pull/12948

PR: https://git.openjdk.org/jdk/pull/12948