r1294: A nice, large, commit...

r1294: A nice, large, commit...

This implements gensec for Samba's server side, and brings gensec up
to the standards of a full subsystem.

This means that use of the subsystem is by gensec_* functions, not
function pointers in structures (this is internal).  This causes
changes in all the existing gensec users.

Our RPC server no longer contains it's own generalised security
scheme, and now calls gensec directly.

Gensec has also taken over the role of auth/auth_ntlmssp.c

An important part of gensec, is the output of the 'session_info'
struct.  This is now reference counted, so that we can correctly free
it when a pipe is closed, no matter if it was inherited, or created by
per-pipe authentication.

The schannel code is reworked, to be in the same file for client and
server.

ntlm_auth is reworked to use gensec.

The major problem with this code is the way it relies on subsystem
auto-initialisation.  The primary reason for this commit now.is to
allow these problems to be looked at, and fixed.

There are problems with the new code:
- I've tested it with smbtorture, but currently don't have VMware and
  valgrind working (this I'll fix soon).
- The SPNEGO code is client-only at this point.
- We still do not do kerberos.

Andrew Bartlett