r176: Improve our fallback code for password changes - this would be better

r176: Improve our fallback code for password changes - this would be better
with more correct NTLMSSP support in client and server, but it will do
for now.

Also implement LANMAN password only in the classical session setup code, but
#ifdef'ed out.  In Samba4, I'll make this run-time so we can torture it.

Lanman passwords over 14 dos characters long could be considered
'invalid' (they are truncated) - so SMBencrypt now returns 'False' if
it generates such a password.

Andrew Bartlett