fix segfault during 31b -> 32b hash table expand
The one signed int 'bucket' was added in nov 2006, and survived until today.
@@ -217,7 +217,7 @@ static void *assoc_maintenance_thread(void *arg) {
/* There is only one expansion thread, so no need to global lock. */
for (ii = 0; ii < hash_bulk_move && expanding; ++ii) {
item *it, *next;
- int bucket;
+ unsigned int bucket;
void *item_lock = NULL;
/* bucket = hv & hashmask(hashpower) =>the bucket of hash table
