[jdk17u-dev] RFR: 8313873: java/nio/channels/DatagramChannel/SendReceiveMaxSize.java fails on AIX due to small default RCVBUF size and different IPv6 Header interpretation

[Martin Doerr]

Basically clean backport of [JDK-8313873](https://bugs.openjdk.org/browse/JDK-8313873).

-------------

Commit messages:
 - Backport 486fa08d4b22243443d39efa34c78d7e9eb44775

Changes: https://git.openjdk.org/jdk17u-dev/pull/2496/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2496&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8313873
  Stats: 36 lines in 2 files changed: 27 ins; 3 del; 6 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2496.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2496/head:pull/2496

PR: https://git.openjdk.org/jdk17u-dev/pull/2496