net: use WARN_ON_ONCE() in inet_sock_destruct()

inet_sock_destruct() has four warnings which have been
useful to point to kernel bugs in the past.

However they are potentially a problem because they
could flood the syslog.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/ipv4/af_inet.c

@@ -148,10 +148,10 @@ void inet_sock_destruct(struct sock *sk)
 		return;
 	}
 
-	WARN_ON(atomic_read(&sk->sk_rmem_alloc));
-	WARN_ON(refcount_read(&sk->sk_wmem_alloc));
-	WARN_ON(sk->sk_wmem_queued);
-	WARN_ON(sk_forward_alloc_get(sk));
+	WARN_ON_ONCE(atomic_read(&sk->sk_rmem_alloc));
+	WARN_ON_ONCE(refcount_read(&sk->sk_wmem_alloc));
+	WARN_ON_ONCE(sk->sk_wmem_queued);
+	WARN_ON_ONCE(sk_forward_alloc_get(sk));
 
 	kfree(rcu_dereference_protected(inet->inet_opt, 1));
 	dst_release(rcu_dereference_protected(sk->sk_dst_cache, 1));