r11573: Adding Andrew Bartlett's patch to make machine account

r11573: Adding Andrew Bartlett's patch to make machine account
logons work if the client gives the MSV1_0_ALLOW_SERVER_TRUST_ACCOUNT
or MSV1_0_ALLOW_WORKSTATION_TRUST_ACCOUNT flags. This changes
the auth module interface to 2 (from 1). The effect of this is
that clients can access resources as a machine account if they
set these flags. This is the same as Windows (think of a VPN
where the vpn client authenticates itself to a VPN server
using machine account credentials - the vpn server checks
that the machine password was valid by performing a machine
account check with the PDC in the same was as it would a
user account check. I may add in a restriction (parameter)
to allow this behaviour to be turned off (as it was previously).
That may be on by default.
Andrew Bartlett please review this change carefully.
Jeremy.