ioq: Copy ring_ops from the previous thread

Otherwise threads 2-N won't use io_uring at all!  Oops.

Fixes: 8bc72d6 ("ioq: Probe for supported io_uring operations")

src/ioq.c

@@ -850,6 +850,7 @@ static int ioq_ring_init(struct ioq *ioq, struct ioq_thread *thread) {
 
  if (prev) {
  // Initial setup already complete
+ thread->ring_ops = prev->ring_ops;
  return 0;
  }
 
@@ -916,12 +917,14 @@ static void ioq_thread_join(struct ioq_thread *thread) {
 }
 
 struct ioq *ioq_create(size_t depth, size_t nthreads) {
- struct ioq *ioq = ZALLOC_FLEX(struct ioq, threads, nthreads);
+ struct ioq *ioq = ALLOC_FLEX(struct ioq, threads, nthreads);
  if (!ioq) {
  goto fail;
  }
 
  ioq->depth = depth;
+ ioq->size = 0;
+ ioq->cancel = false;
 
  ARENA_INIT(&ioq->ents, struct ioq_ent);