r8700: Propmted by tridge's need to do plaintext auth in ejs, rework the

r8700: Propmted by tridge's need to do plaintext auth in ejs, rework the
user_info strcture in auth/

This moves it to a pattern much like that found in ntvfs, with
functions to migrate between PAIN, HASH and RESPONSE passwords.

Instead of make_user_info*() functions, we simply fill in the control
block in the callers, per recent dicussions on the lists.  This
removed a lot of data copies as well as error paths, as we can grab
much of it with talloc.

Andrew Bartlett
(This used to be commit ecbd2235a3e2be937440fa1dc0aecc5a047eda88)