Refactor TTY code to honor runlevels and use I/O plugin to watch /dev

Add support for runlevels to tty command and support for reading baud
rate and TERM variable from finit.conf.

The tty-watcher thread has been converted to a standard I/O plugin.

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

sig.c

@@ -49,13 +49,6 @@
 
 static int stopped = 0;
 
-/* Signal safe sleep ... we get a lot of SIGCHLD at reboot */
-void do_sleep(unsigned int sec)
-{
-	while ((sec = sleep(sec)))
-		;
-}
-
 void do_shutdown (int sig)
 {
 	touch(SYNC_SHUTDOWN);