Now, du works better:
- the depth of hierarchy du can process is no longer limited by
- the user's stack size (nftw uses recursion, the fts implementation
- doesn't)
+ the user's stack size (nftw uses explicit recursion, the fts
+ implementation doesn't)
- works even when run from an inaccessible directory
- du -D now dereferences all symlinks specified on the command line,
not just the ones that reference directories (FIXME: confirm