[krbdev.mit.edu #8167] LDAP KDB module does not build against Solaris native LDAP library

[Greg Hudson via RT]

replace_rdn() (added by ticket 8065) also does not work with the Solaris 
LDAP, because it depends on ldap_str2dn().  The approach taken in 
krb5_ldap_policydn_to_name() is to have one implementation using 
ldap_str2dn() and one using ldap_explode_dn(), but that may not work here 
because there is no obvious inverse of ldap_explode_dn().