Ticket 47591 - entries with empty objectclass attribute value can be hidden
Bug Description: The problem is that for the empty value
it is compared to "ldapsubentry" and "nstombstone"
and with length 0, this is always true.
Fix Description: add a check bv_len >= strlen(valuetocompare)
or bv_len == strlen(valuetocompare)
define constants for lengths
Reviewed by: richm, thanks