GNUmifluz: CIRCLEQ_REMOVE

do { \
 if ((elm)->field.cqe_next == (void *)(head)) \
 (head)->cqh_last = (elm)->field.cqe_prev; \
 else \
 (elm)->field.cqe_next->field.cqe_prev = \
 (elm)->field.cqe_prev; \
 if ((elm)->field.cqe_prev == (void *)(head)) \
 (head)->cqh_first = (elm)->field.cqe_next; \
 else \
 (elm)->field.cqe_prev->field.cqe_next = \
 (elm)->field.cqe_next; \
} while (0)