global: start relying on timeout_remove(NULL) being a no-op

Cleanup performed with the following semantic patch:

	@@
	expression E;
	@@

	- if (E != NULL) {
	- 	timeout_remove(&E);
	- }
	+ timeout_remove(&E);

src/lib-sieve/storage/ldap/sieve-ldap-db.c

@@ -322,8 +322,7 @@ static int db_ldap_connect_finish(struct ldap_connection *conn, int ret)
 		return -1;
 	}
 
-	if (conn->to != NULL)
-		timeout_remove(&conn->to);
+	timeout_remove(&conn->to);
 	conn->conn_state = LDAP_CONN_STATE_BOUND;
 	sieve_storage_sys_debug(storage, "db: "
 		"Successfully bound (dn %s)",
@@ -653,8 +652,7 @@ static int db_ldap_bind(struct ldap_connection *conn)
 	conn->conn_state = LDAP_CONN_STATE_BINDING;
 	conn->default_bind_msgid = msgid;
 
-	if (conn->to != NULL)
-		timeout_remove(&conn->to);
+	timeout_remove(&conn->to);
 	conn->to = timeout_add(DB_LDAP_REQUEST_LOST_TIMEOUT_SECS*1000,
 			       ldap_connection_timeout, conn);
 	return 0;
@@ -934,8 +932,7 @@ static void db_ldap_conn_close(struct ldap_connection *conn)
 	conn->conn_state = LDAP_CONN_STATE_DISCONNECTED;
 	conn->default_bind_msgid = -1;
 
-	if (conn->to != NULL)
-		timeout_remove(&conn->to);
+	timeout_remove(&conn->to);
 
 	if (conn->pending_count != 0) {
 		requests = array_idx(&conn->request_array, 0);

src/managesieve-login/client.c

@@ -341,8 +341,7 @@ static void managesieve_client_input(struct client *client)
 			/* FIXME: Can't do untagged responses with managesieve. Any other ways?
 			client_send_ok(client, AUTH_SERVER_WAITING_MSG);
 			*/
-			if (client->to_auth_waiting != NULL)
-				timeout_remove(&client->to_auth_waiting);
+			timeout_remove(&client->to_auth_waiting);
 
 			client->input_blocked = TRUE;
 			break;

src/managesieve/managesieve-client.c

@@ -252,8 +252,7 @@ void client_destroy(struct client *client, const char *reason)
 
 	managesieve_parser_destroy(&client->parser);
 	io_remove(&client->io);
-	if (client->to_idle_output != NULL)
-		timeout_remove(&client->to_idle_output);
+	timeout_remove(&client->to_idle_output);
 	timeout_remove(&client->to_idle);
 
 	/* i/ostreams are already closed at this stage, so fd can be closed */
@@ -304,8 +303,7 @@ void client_disconnect(struct client *client, const char *reason)
 	i_stream_close(client->input);
 	o_stream_close(client->output);
 
-	if (client->to_idle != NULL)
-		timeout_remove(&client->to_idle);
+	timeout_remove(&client->to_idle);
 	client->to_idle = timeout_add(0, client_destroy_timeout, client);
 }