util: util_ntdb.c

util: util_ntdb.c

The first function is ntdb_new: this is preferred over ntdb_open, as
it makes the ntdb_context returned (and all NTDB_DATA returned from
ntdb_fetch) valid talloc pointers.

The API is very similar to tdb_wrap_open().

Note that we handle $TDB_NO_FSYNC here, since ntdb doesn't do that
hack (and it's great for speeding up testing!).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>