SMB signing updates - this gets NTLMSSP signing workin to the point where I

SMB signing updates - this gets NTLMSSP signing workin to the point where I
just need to get the verifiction code working - we get back a signiture from
the server, and just can't verify it yet.

This also brings the short-packet checks into common code, and breaks the
connection if the server sends a signed reply, on an established connection,
that fails the test.

This breaks our read/write code at the moment, as we need to keep a list
of outstanding packets.

(signing is not enabled by default, unless the server demands it)

Not for 3.0 till I fix the outstanding packet list.

Andrew Barlett