smaba4kpasswd will be used to test the kpasswdd componet of the KDC
(which is up until now untested), and rkpty is an expect-like wrapper
we can use to blackbox that utility.
Andrew Bartlett
Since it's a function it just sets the local pointer to NULL and basically
is an equivalent to free().
It also claims it's being used for callbacks but isn't used that way
anywhere.