[jdk17u-dev] RFR: 8311645: Memory leak in jspawnhelper spawnChild after JDK-8307990 [v2]

[Volker Simonis]

> This is a clean backport of [JDK-8311645: Memory leak in jspawnhelper spawnChild after JDK-8307990](https://bugs.openjdk.org/browse/JDK-8311645) which is a follow-up fix for [JDK-8307990: jspawnhelper must close its writing side of a pipe before reading from it](https://bugs.openjdk.org/browse/JDK-8307990) which is currently [under review](https://github.com/openjdk/jdk17u-dev/pull/2013).
> 
> This backport depends on [pr/2013](https://github.com/openjdk/jdk17u-dev/pull/2013) and will be pushed once that one has been reviewed and approved.

Volker Simonis 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.

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Changes:
  - all: https://git.openjdk.org/jdk17u-dev/pull/2017/files
  - new: https://git.openjdk.org/jdk17u-dev/pull/2017/files/6b7e6042..6b7e6042

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2017&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2017&range=00-01

  Stats: 0 lines in 0 files changed: 0 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2017.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2017/head:pull/2017

PR: https://git.openjdk.org/jdk17u-dev/pull/2017