Fix #175: Ensure finit does not acquire 'dev' as controlling TTY

When starting a getty Finit checks first that the configured TTY device
actually exists and is a TTY.  This patch, by Tobias Waldekranz, ensures
Finit (PID 1) doesn't acquire the TTY device as a controlling TTY.  If
that happens PID 1 will get all signals sent to the process actually
started with the device as its controlling TTY.

Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/tty.c

@@ -229,7 +229,7 @@ int tty_exists(char *dev)
 	struct termios c;
 	int fd, rc;
 
-	fd = open(dev, O_RDWR);
+	fd = open(dev, O_RDWR | O_NOCTTY);
 	if (-1 == fd)
 		return 0;