Replace depricated krb5_get_init_creds_opt_init()

New KRB5 function 
krb5_get_init_creds_opt_alloc(krb5_context context, krb5_get_init_creds_opt** opt) 
with 
krb5_get_init_creds_opt_free(krb5_context context, krb5_get_init_creds_opt* opt).