sshd: do not resolve refused client hostname

[glebius]

Summary

This is a compromise between POLA and practical reasoning. We don't
want to block the main server loop in an attempt to resolve. But we
need to keep the format of the logged message as is, for sake of
sshguard and other scripts. So let's print just the IP address twice,
this is what libwrap's refuse() would do if it failed to resolve.

PR: 269456

[philip]

I think this is a good compromise. I suggest some minor grammar/wording changes to clarify the comment. Nothing consequential. This looks good to me.

crypto/openssh/sshd.c

1299–1314