The lib/kadm5/test_marshall program allows one to construct and check
encodings for various struct types for which we have
{kadm5,krb5}_{ret,store}_<type>() functions.
Currently supported are:
- krb5_keyblock
- krb5_principal
- krb5_times
- krb5_address
- krb5_addresses
- krb5_authdata
- krb5_creds
- krb5_key_data
- krb5_tl_data
- kadm5_principal_ent_rec
With this we'll be able to a) construct test vectors, b) use those to
drive fuzzing with AFL or other fuzzers.