Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFH (r237568, r255422, r255460, r255766, r255767, r255774, r255829,
r256126, r257954, r261320, r261499, r263691, r263712): upgrade to
OpenSSH 6.6p1 via 6.3p1, 6.4p1 and 6.5p1.

Differences relative to head:

- No DNSSEC support since stable/9 does not have LDNS
- Sandboxing off by default, and uses rlimit instead of Capsicum
- ED25519 moved to the bottom of the order of preference to avoid
"new public key" warnings

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Upgrade to OpenSSH 5.2p1.

MFC after: 3 months

Upgrade to OpenSSH 5.1p1.

I have worked hard to reduce diffs against the vendor branch. One
notable change in that respect is that we no longer prefer DSA over
RSA - the reasons for doing so went away years ago. This may cause
some surprises, as ssh will warn about unknown host keys even for
hosts whose keys haven't changed.

MFC after: 6 weeks

Vendor import of OpenSSH 5.1p1

Vendor import of OpenSSH 4.9p1 for posterity's sake

Vendor import of OpenSSH 4.7p1 for posterity's sake