r13601: * Remove unused code from pdb_ldap.c

r13601: * Remove unused code from pdb_ldap.c
* Add a 'struct passwd *' to the struct samu for later reference
  (I know this may be controversial but its easily reverted which is
  is why I'm checking this is as a seaparate patch before I get
  too deep).
* Remove unix_homedir from struct samu {} and update the pdb wrapper
  functions associated with it.
(This used to be commit 92c251fdf0f1f566cfeca3c75ba2284b644aef5d)