RFR: 8256427: Test com/sun/jndi/dns/ConfigTests/PortUnreachable.java does not work on AIX

[Christoph Langer]

The test com/sun/jndi/dns/ConfigTests/PortUnreachable.java is not working on AIX.

It tests that when a DNS server is unreachable it fails quickly with a PortUnreachableException due to ICMP Destination Unreachable packets received and not having to wait for the full timeout interval.
Unfortunately, on AIX such ICMP packets are not received, so the only exception cause will be the timeout. Hence, this test can't work on AIX, so it should not be executed there.

At SAP, we had this test excluded for a long time already in our private exclude list for AIX. I suggest this test update to be the final solution.

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Commit messages:
 - Test jdk/com/sun/jndi/dns/ConfigTests/PortUnreachable.java does not work on AIX

Changes: https://git.openjdk.java.net/jdk/pull/1241/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1241&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8256427
  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1241.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1241/head:pull/1241

PR: https://git.openjdk.java.net/jdk/pull/1241