Feature or enhancement

Extend socket's AF_NETLINK support to FreeBSD.

Pitch

FreeBSD 13.2-RELEASE was the first FreeBSD release with a solid support of netlink.
Previously this was Linux only technology, but has established itself as a standard: https://www.rfc-editor.org/rfc/rfc3549

Previous discussion

This is all pretty new, so I am unaware of previous discussions.

Linked PRs

• GH-107812: extend socket's netlink support to FreeBSD #107813