mount_cd9660 broken with multi-session CDs

mount_cd9660 doesn't pass the correct 'ssector' option to the kernel
so it's unable to mount multi-session disks.

this small patch fixes it for me:

--- /usr/src/sbin/mount_cd9660/mount_cd9660.c	Thu Dec 15 02:01:38 2005
+++ ./mount_cd9660.c	Sun Dec 18 00:07:46 2005
_at__at_ -175,7 +175,7 _at__at_
 	build_iovec(&iov, &iovlen, "fstype", fstype, (size_t)-1);
 	build_iovec(&iov, &iovlen, "fspath", mntpath, (size_t)-1);
 	build_iovec(&iov, &iovlen, "from", dev, (size_t)-1);
-	build_iovec(&iov, &iovlen, "ssector", &ssector, sizeof ssector);
+	build_iovec_argf(&iov, &iovlen, "ssector", "%d", ssector);
 
 	if (nmount(iov, iovlen, mntflags) < 0)
 		err(1, "%s", dev);