autoconf check for socklen_t

[Darren_Hall at progressive.com]

> For portability changes, it is best to send the via this list. Feel
> free to send any other patches as well, I feed them back to the
> OpenBSD people if I think they are relevant.

I'll have all the socklen_t patches sent back to the list soon.

> Does 1.2.1pre22 (with your patch) work correctly on AIX?

I've got it to compile via native compiler and working on AIX 4.2.1.  I
will see if I can check out 4.3.2 as well.

The utmp support works, I've confirmed X forwarding, and both types of
cipher.
I had problems with scp, and had to explicitly setup a .ssh/environment
file
to include the /usr/local/bin.

I'll have to download the latest version and check to see if _PATH_STDPATH
(which isn't defined on AIX) includes $bindir if not already there at
compile
time.