TTY: Major overhaul, move to built-in getty

The TTY handling in Finit has always been a bit of a patch work.  This
commit is an attempt at a first cleanup and simplification.

Included is a brand new built-in getty which should work fine on both
virtual and serial consoles.  It is however completely untested on the
latter serial consoles.

Still TODO: add support for /etc/securetty, add support for actually
setting TERM when calling /bin/login.

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

helpers.h

@@ -83,7 +83,7 @@ void    set_hostname    (char **hostname);
 int     complete        (char *cmd, int pid);
 int     run             (char *cmd);
 int     run_interactive (char *cmd, char *fmt, ...);
-pid_t   run_getty       (char *cmd, char *args[], char *tty, int console);
+pid_t   run_getty       (char *tty, char *speed, char *term, int console);
 int     run_parts       (char *dir, char *cmd);
 
 #endif /* FINIT_HELPERS_H_ */