fixes #1673 High CPU usage with TLS

The aio for connections was meant to have an infinite sleep (no
timeout), but was getting an initial value of zero, so we were spinning
on accept.

src/supplemental/tls/tls_common.c

@@ -867,6 +867,7 @@ tls_alloc(tls_conn **conn_p, nng_tls_config *cfg, nng_aio *user_aio)
 	nni_aio_list_init(&conn->send_queue);
 	nni_aio_list_init(&conn->recv_queue);
 	nni_mtx_init(&conn->lock);
+	nni_aio_set_timeout(&conn->conn_aio, NNG_DURATION_INFINITE);
 	nni_aio_set_timeout(&conn->tcp_send, NNG_DURATION_INFINITE);
 	nni_aio_set_timeout(&conn->tcp_recv, NNG_DURATION_INFINITE);