pf_state_compare_id
static inline int pf_state_compare_id(const struct pf_state *,
RBT_GENERATE(pf_state_tree_id, pf_state, entry_id, pf_state_compare_id);
RBT_PROTOTYPE(pf_state_tree_id, pf_state, entry_id, pf_state_compare_id);