[jdk17u-dev] RFR: 8311645: Memory leak in jspawnhelper spawnChild after JDK-8307990 [v3]

[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. The pull request contains three additional commits since the last revision:

 - Merge master
 - Backport 401c3dea5d8823bc9c0f40506ddad46e983ebf68
 - Backport 39f6d807dbbe0c9ecd72fe2f76bfbc3091b43c80

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

Changes:
  - all: https://git.openjdk.org/jdk17u-dev/pull/2017/files
  - new: https://git.openjdk.org/jdk17u-dev/pull/2017/files/6b7e6042..0aa84b3b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2017&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2017&range=01-02

  Stats: 12973 lines in 193 files changed: 7227 ins; 1348 del; 4398 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