SMB Winbind NT Authentication (Password/MsCHAPv2)

User can authenticate against Windows AD Server from Linux VPN SoftEther Server. 

- the linux server is member of the domain
- the authentication takes place due to ntlm_auth
- if the groupname is set in u->GroupName (VPN UserManagement) it will represent the AD Group and is required

a timeout for auth_ntlm should be implemented in production release