Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Very large style makeover.

1) ANSIfy.
2) Clean up ifdefs so that
a) ones that never/always apply are appropriately either
fully removed, or just the #if junk is removed.
b) change #if defined(FOO) for appropiate values of FOO.
(currently AUTHENTICATION and ENCRYPTION)
3) WARNS=2 fixing
4) GC other unused stuff

This code can now be unifdef(1)ed to make non-crypto telnet.

Fix world by trimming an extra comment terminator.

Add Berkeley copyright to SRA.

This is by the kind permission of Dave Safford, formerly of TAMU who wrote the
original code. Here is an excerpt of the e-mail exchange concerning this
issue:

Dave Safford wrote:
>Nick Sayer wrote:
>> Some time ago we spoke about SRA and importing it into FreeBSD. I forgot to
>> ask if you had a prefered license boilerplate for the top of the files. It
>> has come up recently, and the SRA code in FreeBSD doesn't have one.

>I really have no preference - use whatever is most convenient in the
>FreeBSD environment.

>dave safford

This is the standard BSD license with clause 3 removed and clause 4
suitably renumbered.

MFC after: 1 day

Forced commit. This is to try and help folks that used the international
crypto repo and have slightly different files but with the same version.
cvsup in 'checkout mode' has no trouble with this, but cvs can get really
silly about it.

Add missing $FreeBSD$ to files that are NOT still on vendor a branch.

Add SRA authentication to src/crypto/telnet.

SRA does a Diffie-Hellmen exchange and then DES-encrypts the
authentication data. If the authentication is successful, it also
sets up a session key for DES encryption.

SRA was originally developed at Texas A&M University.

This code is probably export restricted (despite the fact that I
originally found it at a University in Germany).

SRA is not perfect. It is vulnerable to monkey-in-the-middle attacks
and does not use tremendously large DH constants (and thus an individual
exchange probably could be factored in a few days on modern CPU
horsepower). It does not, however, require any changes in user or
administrative behavior and foils session hijacking and sniffing.
The goal of this commit is that telnet and telnetd end up in the DES
distribution and that therefore an encrypted session telnet becomes
standard issue for FreeBSD.