queue_shift
queue_shift(rq);
p2 = queue_shift(&q);
p2 = queue_shift(&q);
ip = queue_shift(&iq);
ip = queue_shift(&iq);
n = queue_shift(&workq); /* 'pop' next solvable to work on from queue */
p = queue_shift(&qs);
p = queue_shift(&q); /* get first candidate */
i = queue_shift(&uninstq);
i = queue_shift(&samerepoq);
i = queue_shift(&samerepoq);