Fix the uds_datagram tests with the latest nightly stdlib

[asomers]

io::ErrorKind just replaced most uses of "Other" with "Uncategorized"
and prohibits users from matching on "Uncategorized". So match on the
errno instead.

rust-lang/rust#85746

Motivation

Fix tests on the latest nightly stdlib

Solution

Don't match io::Error::Errorkind to Other or Uncategorized.

[Darksonn]

It's true on FreeBSD, but I didn't check anywhere else. We may end up needing to whitelist a couple of different errnos.

If our CI setup passes with the current list, then we can merge it as is. Of course, if you are aware of any missing errnos, then it'd be nice to add them immediately.

[asomers]

It's true on FreeBSD, but I didn't check anywhere else. We may end up needing to whitelist a couple of different errnos.

If our CI setup passes with the current list, then we can merge it as is. Of course, if you are aware of any missing errnos, then it'd be nice to add them immediately.

Your CI setup passes because it doesn't test on the latest nightly. I'm not aware of any missing errnos, because I haven't tested on any OS but FreeBSD. But eventually somebody will.

[Darksonn]

Right, good point. Let's merge #3953 first.