Account for late initialization of tbb threads

When ThreadInitTools are initialized, an internal counter gets incremented. This counter is decremented on thread termination, and if not zero at the end, an error was reported. However when tbb creates threads late in the game, the counter gets incremented more than expected, and as only the active threads in the thread pool get terminated, the counter doesn't reach zero. This isn't serious, so we change the error to an info message for termination. It is still an error if the counter doesn't equal the thread pool size after the initial initialization however.