mkfs.erofs with version < 1.6 does not support the -L option. Let's detect the version of mkfs.erofs and skip the label tests if it is not supported. Suggested-by: Glenn Washburn <development@efficientek.com> Signed-off-by: Yifan Zhao <zhaoyifan@sjtu.edu.cn> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>