btrfs: incremental send after replacing a top level inode

btrfs: incremental send after replacing a top level inode

Test that an incremental send operation does not fail when a new
inode replaces an old inode that has the same number but different
generation, and both are direct children of the subvolume/snapshot
root.

This is fixed by the following patch for the linux kernel:

  "Btrfs: send, fix failure to rename top level inode due to name
   collision"

Signed-off-by: Robbie Ko <robbieko@synology.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>