[PATCH V2] Add RFC 8335 Definitions from Linux 5.12

[Florian Weimer]

* Andreas Roeseler:

> RFC 8335 defines the network utility PROBE, which builds off of the
> capabilities of Ping to query more detailed interface information from
> networking nodes.
>
> The definitions included in this patchset have been accepted into the
> linux net-next branch and will be included in Linux 5.12. This
> patchset adds the same definitions to the glibc for use in the
> iputils package.
>
> The relevant commits for the Linux definitions can be found here:
> https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=2b246b2569cd2ac6ff700d0dce56b8bae29b1842
> https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=750f4fc2a12f6632b5aa04526bf57fa06bfe8467

The names should be teh same on the glibc and Linus side.  These commits
still use the old names.

Thanks,
Florian