GNUmifluz: SH_TAILQ_INSERT_TAIL

do { \
 (elm)->field.stqe_next = -1; \
 (elm)->field.stqe_prev = \
 -SH_PTR_TO_OFF(head, elm) + (head)->stqh_last; \
 if ((head)->stqh_last == \
 SH_PTR_TO_OFF((head), &(head)->stqh_first)) \
 (head)->stqh_first = SH_PTR_TO_OFF(head, elm); \
 else \
 *SH_TAILQ_LAST(head) = -(head)->stqh_last + \
 SH_PTR_TO_OFF((elm), &(elm)->field.stqe_next) + \
 SH_PTR_TO_OFF(head, elm); \
 (head)->stqh_last = \
 SH_PTR_TO_OFF(head, &((elm)->field.stqe_next)); \
} while (0)