Merge topic branch t/afs-ls-a into master

Merge topic branch t/afs-ls-a into master

A new feature for the ls command. Unfortunately, several bugs were
found after the topic graduated to next, so the series contains a few
fixup commits on top of the single patch which implements the feature.

* refs/heads/t/afs-ls-a:
  afs: Really fix memory leak in mood_load().
  afs: Fix memory leak in mood_load().
  playlist: Fix error handling of playlist_load().
  server: Fix NULL pointer dereference in com_ls().
  Implement ls --admissible=m/foo.