openvt,getty,vfork_daemon_rexec,mount: tighten up fd cleanup code

(will close all fd's > 2 on daemonization now)
getty: fix "getty -" support, and also do not try to chown/chmod "-"
telnetd: fix "lost ctty" bug
Yet another attempt on saner function names:
bb_sanitize_server_stdio(0/1) -> bb_sanitize_stdio() + bb_daemonize();

libbb/vfork_daemon_rexec.c

@@ -35,8 +35,8 @@ void vfork_daemon_rexec(int nochdir, int noclose,
 		dup2(fd, STDIN_FILENO);
 		dup2(fd, STDOUT_FILENO);
 		dup2(fd, STDERR_FILENO);
-		if (fd > 2)
-			close(fd);
+		while (fd > 2)
+			close(fd--);
 	}
 
 	vfork_args = xzalloc(sizeof(char *) * (argc + 3));