KRB5_KDB_FLAG_PROTOCOL_TRANSITION
#define KRB5_KDB_FLAGS_S4U ( KRB5_KDB_FLAG_PROTOCOL_TRANSITION | \
t->flags |= KRB5_KDB_FLAG_PROTOCOL_TRANSITION;
if (isflagset(c_flags, KRB5_KDB_FLAG_PROTOCOL_TRANSITION))
(client != NULL && (flags & KRB5_KDB_FLAG_PROTOCOL_TRANSITION))) {