btrfs: add test for btrfs incremental send

btrfs: add test for btrfs incremental send

Regression test for a btrfs incremental send issue where invalid paths for
utimes, chown and chmod operations were sent to the send stream, causing
btrfs receive to fail.

If a directory had a move/rename operation delayed, and none of its parent
directories, except for the immediate one, had delayed move/rename operations,
after processing the directory's references, the incremental send code would
issue invalid paths for utimes, chown and chmod operations.

This issue is fixed by the following linux kernel btrfs patch:

    Btrfs: fix send issuing outdated paths for utimes, chown and chmod

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>