Ticket 47421 - memory leaks in set_krb5_creds
    
    Bug Description:  Valgrind shows memory leaks in set_krb5_creds()
    
    Fix description:  krb5_unparse_name() allocates/returns the principle name.
                      But we can call this function twice without freeing the first
                      returned value.
    
    https://fedorahosted.org/389/ticket/47421
    
    Reviewed by: richm(Thanks!)
    (cherry picked from commit db124a2711576de2dd0009528d60b2860e815210)
    (cherry picked from commit c1dcfc605b56a61199d827f213c490e109d8279e)