RFR: 8354530: AIX: sporadic unexpected errno when calling setsockopt in Net.joinOrDrop

[Arno Zeller]

On AIX we have sporadic EAGAIN errors when calling setsockopt. This is undocumented, but has been seen in tests. 
Further test did show that it might not be enough to only try it once again. In our daily test environment we have seen no more unexpected exceptions when we retried 3 times.

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Commit messages:
 - Retry 3 times
 - Update copyright
 - JDK-8354530 : AIX: sporadic unexpected errno when calling setsockopt in Net.joinOrDrop.

Changes: https://git.openjdk.org/jdk/pull/24996/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24996&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8354530
  Stats: 11 lines in 1 file changed: 10 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/24996.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24996/head:pull/24996

PR: https://git.openjdk.org/jdk/pull/24996