open_pipes() bugfix

+ write "exit" to STDERR (like bash)
+ set_last_exit_status() on CTRL-C

srcs/shell_loop.c

@@ -53,7 +53,7 @@ static char	*read_input(char *prompt, t_all *c)
 	sigaction(SIGINT, &signal_behaviour, NULL);
 	if (!line_input)
 	{
-		write(1, "exit\n", 5);
+		write(STDERR_FILENO, "exit\n", 5);
 		exit_free(c, get_last_exit_status());
 	}
 	return (line_input);