fstests: btrfs, test for send with clone operations

fstests: btrfs, test for send with clone operations

Test that an incremental send operation which issues clone operations
works for files that have a full path containing more than one parent
directory component.

This used to fail before the following patch for the linux kernel:

  "[PATCH] Btrfs: send, fix extent buffer tree lock assertion failure"

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>