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

Pull in all the OpenSSH bits that we'd previously left out because we
didn't use them. This will make future merges from the vendor tree much
easier.

Approved by: re (gjb)

Vendor import of OpenSSH 6.0p1.

Vendor import of OpenSSH 5.5p1

Vendor import of OpenSSH 5.4p1

Vendor import of OpenSSH 5.2p1

Vendor import of OpenSSH 5.1p1

Oops, remove svn:keyword again.

Vendor import of OpenSSH 4.6p1 for posterity's sake