Ticket #48252 - db2index creates index entry from deleted records
    
    Bug Description: When an entry is deleted, its indexed attribute values
    are also removed from each index file.  But if the entry is turned to be
    a tombstone entry, reindexing adds the removed attribute value back to
    the index file.
    
    Fix Description: In the reindexing function ldbm_back_ldbm2index, if the
    entry is a tombstone entry, it skips reindexing operation unless the target
    attribute is entryrdn or objectclass.  If it is reindexing the objectclass,
    it indexes just for the key "=nstombstone".
    
    https://fedorahosted.org/389/ticket/48252
    
    Reviewed by mreynolds@redhat.com (Thank you, Mark!!)
    
    (cherry picked from commit ca4d38dff3bd820af2bf60c9bcc82fd64aac2556)
    (cherry picked from commit 86b96278871d8b08f7c6a75379935c2183f6668f)