xfs: destroy seen inode bitmap when we fail to add a dirpath

In the Linux kernel, the following vulnerability has been resolved: xfs: destroy seen inode bitmap when we fail to add a dirpath LOLLM observes a memory leak in xchk_dirtree_create_path if we create the directory path object but appending the name to the path fails. When this happens, we don't tear down the (empty) seen inode bitmap. This is a pretty trivial error, but let's not leave logic bombs. Do the same for a similar bug in xrep_dirtree_create_adoption_path.