1. Originally, configuration attributes are designed not to allow
adding or deleting, but to allow just replacing. Due to a defect
in checking the add operation, adding (LDAP_MOD_ADD) is not rejected.
Instead of fixing the add checking to disallow adding, this patch
logs the operation in the error log.
2. On the other hand, deleting configuration attributes is rejected
by LDAP_UNWILLING_TO_PERFORM. We have a request that some attributes
need to allow to delete. This patch introduces a config attribute
nsslapd-allowed-to-delete-attrs, which value is configuration
attributes separated by a space ' '. If an attribute is in the list,
the attribute is allowed to delete. The delete operation is also
logged in the error log.