RFR: 8279329: Remove hardcoded IPv4 available policy on Windows

Wed Feb 2 13:11:06 UTC 2022

On Wed, 2 Feb 2022 08:31:08 GMT, Masanori Yano <myano at openjdk.org> wrote:

> I added socket connection check same as IPv6_supported().
> Before this fix, when IPv4 is uninstalled (called `netsh interface ipv4 uninstall`), and set property `-Djava.net.preferIPv4Stack=true`, java.net.InetAddress.PLATFORM_LOOKUP_POLICY.characteristics is always set to 1(IPv4), because IPv4_supported() always returns TRUE. After applied this fix, java.net.InetAddress.PLATFORM_LOOKUP_POLICY.characteristics is set to 2(IPv6). 
> It looks fine that IPv4_supported() returns FALSE.
> Would you review this fix?

This looks reasonable.

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Marked as reviewed by dfuchs (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/7317