btrfs-progs: mkfs-tests: Add test case to verify the --rootdir size limit
Add a test case to ensure we can create a 350M fs with 128M rootdir.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>