2f58df9a8f
that the caller allocate the pool_item_header when it allocates the pool page, so we can avoid a locking pitfall (sleeping with a simple lock held). Also revive pool_prime(), as there are some letigimate uses of it, but in doing so, eliminate some of the bogosities of the old version (i.e. don't do an implicit "setlowat", just prime the pool, and incr the minpages for each additional page we add, and compute the number of pages to prime in a way that callers would expect).