Bug#813806: f2fs.fsck segfaults on boot

[Martin Blumenstingl]

This is a bug which was fixed in upstream's -dev branch:
https://git.kernel.org/cgit/linux/kernel/git/jaegeuk/f2fs-tools.git/commit/fsck/mount.c?h=dev&id=231fc70f6e9d57658393911c705346b061f23513