common/btrfs: add a _require_btrfs_no_nodatasum helper
Add a _require_btrfs_no_nodatasum helper to skip a test if the nodatasum
mount option is give, as we do have several tests that fail, for several
reasons, when that mount option is passed.
Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Reviewed-by: Anand Jain <anand.jain@oracle.com> Signed-off-by: Zorro Lang <zlang@kernel.org>