krb5_set_principal_realm
retval = krb5_set_principal_realm(context, my_principal, realm);
retval = krb5_set_principal_realm(context, creds.server, realm);
retval = krb5_set_principal_realm(kpropd_context, server, realm);
krb5_error_code KRB5_CALLCONV krb5_set_principal_realm