RFR: 8305089: Implement missing socket options on AIX [v5]

[Varada M]

> Breaking this into two parts : 
> 
> 1. Implementing socket options for AIX 
> 2. DontFragmentTest failure 
> 
> - Implementing socket options for AIX :
> 
> Unlike the linux, windows and macOS, AIX uses the default implementation for socket options such as ipDontFragmentSupported(), keepAliveOptionsSupported(), setTcpkeepAliveProbes, getTcpkeepAliveProbes, setQuickAck, getQuickAck and more, where it either returns false or exception. These options can be implemented on AIX with the supported flags like SO_PEERID, TCP_NODELAYACK is the equivalent AIX option for TCP_QUICKACK and IPPROTO_TCP, IP_DONTFRAG. 
> 
> - DontFragment test failure :
> 
> DontFragmentTest.java fails with a runtime exception : “IP_DONTFRAGMENT should be supported” because the supportOptions doesn’t contain IP_DONTFRAGMENT flag.
> 
> Reported Issue :  [JDK-8305089](https://bugs.openjdk.org/browse/JDK-8305089)

Varada M has updated the pull request incrementally with one additional commit since the last revision:

  added SO_PEERID failed

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/13240/files
  - new: https://git.openjdk.org/jdk/pull/13240/files/5b2fd5e2..d595d962

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13240&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13240&range=03-04

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/13240.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13240/head:pull/13240

PR: https://git.openjdk.org/jdk/pull/13240