GNUmifluz: SH_TAILQ_REMOVE

do { \
 if ((elm)->field.stqe_next != -1) { \
 SH_TAILQ_NEXTP(elm, field, type)->field.stqe_prev = \
 (elm)->field.stqe_prev + \
 SH_PTR_TO_OFF(SH_TAILQ_NEXTP(elm, \
 field, type), elm); \
 *SH_TAILQ_PREVP(elm, field) += elm->field.stqe_next; \
 } else { \
 (head)->stqh_last = (elm)->field.stqe_prev + \
 SH_PTR_TO_OFF(head, elm); \
 *SH_TAILQ_PREVP(elm, field) = -1; \
 } \
} while (0)