[jdk21u-dev] RFR: 8347143: [aix] Fix strdup use in os::dll_load

[Goetz Lindenmaier]

I would like to backport this follow-up to [8334217: [AIX] Misleading error messages after JDK-8320005](https://github.com/openjdk/jdk21u-dev/commit/ea6b681cbe0e7c0cc7d1b5fb4dcc2f82e40acf60)

Resolved copyright, probably clean.

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Commit messages:
 - backport d5320197995bbd4423e660c61a4677428e70819c

Changes: https://git.openjdk.org/jdk21u-dev/pull/2198/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=2198&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8347143
  Stats: 17 lines in 1 file changed: 7 ins; 4 del; 6 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/2198.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/2198/head:pull/2198

PR: https://git.openjdk.org/jdk21u-dev/pull/2198