RFR: 8361873: [GCC static analyzer] exec_md.c forkedChildProcess potential double 'close' of file descriptor '3' [v3]

[Chris Plummer]

> Fix gcc warning about double close. forkedChildProcess() calls closeDescriptors(), which always closes STDERR_FILENO + 1 and STDERR_FILENO + 2. However, if it fails at some point after that, then forkedChildProcess() will attempt to close these same two files again. Fixed by making forkedChildProcess() no longer attempt to close these two files.
> 
> I first verified the warning by configuring with --with-extra-cflags=-fanalyzer, and then verified the fix by doing the same.
> 
> Tested by running jdi nsk test. I'll add some more CI testing.

Chris Plummer has updated the pull request incrementally with one additional commit since the last revision:

  Update comment

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Changes:
  - all: https://git.openjdk.org/jdk/pull/26487/files
  - new: https://git.openjdk.org/jdk/pull/26487/files/4095d6ce..49ca5abb

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26487&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26487&range=01-02

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/26487.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26487/head:pull/26487

PR: https://git.openjdk.org/jdk/pull/26487