openssh: update to OpenSSH v8.7p1

Some notable changes, from upstream's release notes:

- sshd(8): Remove support for obsolete "host/port" syntax.
- ssh(1): When prompting whether to record a new host key, accept the key
fingerprint as a synonym for "yes".
- ssh-keygen(1): when acting as a CA and signing certificates with an RSA
key, default to using the rsa-sha2-512 signature algorithm.
- ssh(1), sshd(8), ssh-keygen(1): this release removes the "ssh-rsa"
(RSA/SHA1) algorithm from those accepted for certificate signatures.
- ssh-sk-helper(8): this is a new binary. It is used by the FIDO/U2F
support to provide address-space isolation for token middleware
libraries (including the internal one).
- ssh(1): this release enables UpdateHostkeys by default subject to some
conservative preconditions.
- scp(1): this release changes the behaviour of remote to remote copies
(e.g. "scp host-a:/path host-b:") to transfer through the local host
by default.
- scp(1): experimental support for transfers using the SFTP protocol as
a replacement for the venerable SCP/RCP protocol that it has
traditionally used.

Additional integration work is needed to support FIDO/U2F in the base
system.

Deprecation Notice
------------------

OpenSSH will disable the ssh-rsa signature scheme by default in the
next release.

Reviewed by: imp
MFC after: 1 month
Relnotes: Yes
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D29985

Upgrade to OpenSSH 7.8p1.

Approved by: re (kib@)

Upgrade to OpenSSH 7.2p2.

Upgrade to OpenSSH 7.0p1.

Upgrade to OpenSSH 6.9p1.

Upgrade to OpenSSH 6.8p1.

Upgrade to OpenSSH 6.7p1, retaining libwrap support (which has been removed
upstream) and a number of security fixes which we had already backported.

MFC after: 1 week

Upgrade to OpenSSH 6.6p1.

Upgrade to OpenSSH 6.5p1.

Upgrade to 6.3p1.

Approved by: re (gjb)

Upgrade OpenSSH to 6.1p1.

Upgrade to OpenSSH 5.9p1.

MFC after: 3 months