Add refactored blacklist support to sshd

[• lidl]

Summary

Add refactored blacklist support to sshd

Remove use of #ifdef USE_BLACKLIST / #endif, and change the
calls to of blacklist_init() and blacklist_notify to be
macros defined in the blacklist_client.h file.

Remove redundent initialization attempts from within
blacklist_notify - everything always goes through
blacklistd_init().

Added UseBlacklist option to sshd, which defaults to off.
To enable the functionality, use '-o UseBlacklist=yes' on
the command line, or uncomment in the sshd_config file.

[emaste]

Please upload with full context - instructions available at https://wiki.freebsd.org/CodeReview

[• lidl]

Full diff uploaded, as requested by Ed Maste. Should otherwise be the same as the prior diff.

[• lidl]

Refresh diff with latest code.
Updates based on comments received from des@ in email.

[• lidl]

Latest version of the diff, updated based on des' comments.

[• lidl]

This is the same as the last uploaded diff, only generated with -U99999 so the entire content of any affected files can be viewed through Phabricator.

[wblock]

crypto/openssh/sshd_config.5

1549

Passive -> active. Also, "should" implies a recommendation.

s/should attempt/attempts/

1558

As above:

looks up the remote host name and checks that

[• lidl]

crypto/openssh/sshd_config.5

1558

I'm not going to make this change in this part of the text, as this comes from upstream. While you are correct it could be improved, I don't think that improvement ought to be part of this patch.

[wblock]

crypto/openssh/sshd_config.5

1558

Fair enough.