[krbdev.mit.edu #1491] We do not provide krb524 interface

[Sam Hartman via RT]

We neither install libkrb524.a nor provide the
krb524_convert_creds_kdc API somewhere else.  As such it is impossible
to build aklog against Kerberos 1.3.

This is a show stopper.  We may want to fix my moving
krb5_conv_creds_kdc into libkrb5 or libkrb4.


If we move it into krb5, we need to provide an API that returns
failure when built without krb4 support.