tidy up O_NONBLOCK usage. use libbb functions in stty.

Added O_RDONLY where improves readability. Note: O_RDONLY == 0,
so it is there even if not specified.

function                                             old     new   delta
stty_main                                           1289    1235     -54

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/modutils/modprobe.c b/modutils/modprobe.c
index 0d65d5f..ca85ee7 100644
--- a/modutils/modprobe.c
+++ b/modutils/modprobe.c
@@ -373,7 +373,7 @@
 			 * "If name is NULL, all unused modules marked
 			 * autoclean will be removed".
 			 */
-			if (bb_delete_module(NULL, O_NONBLOCK|O_EXCL) != 0)
+			if (bb_delete_module(NULL, O_NONBLOCK | O_EXCL) != 0)
 				bb_perror_msg_and_die("rmmod");
 		}
 		return EXIT_SUCCESS;