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

[Joachim Kern]

The use of strdup (which is os::strdup because of context) in aix's os::dll_load is odd. The result is nearly unused (it's passed to strrchr, but the original filename could be used instead), so the duplication doesn't seem needed. And the duplicate is free'd using FREE_C_HEAP_ARRAY, which seems wrong.

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Commit messages:
 - JDK-8347143

Changes: https://git.openjdk.org/jdk/pull/23078/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23078&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8347143
  Stats: 14 lines in 1 file changed: 7 ins; 4 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/23078.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23078/head:pull/23078

PR: https://git.openjdk.org/jdk/pull/23078