hide rest of UFN code behind #ifdef LDAP_UFN in preparation
for eventual removal.

garbage input from slapadd or pre-existing database.

fix compiler warnings by including ac/unistd.h and only declaring copy_hostent() when we actually need to use it

s/LDAP_PF_UNIX/LDAP_PF_LOCAL/ so that we actually declare ldap_connect_to_path(). Also fix the decleration to match the function