ITS#8997 - Fix segfault by setting return code value

Fix case with back-ldap where an entry was returned but didn't match the filter being applied by setting the return code value before dropping to cleanup.

servers/slapd/back-ldap/search.c

@@ -1006,6 +1006,7 @@ retry:
 	e = ldap_first_entry( lc->lc_ld, result );
 	if ( e == NULL ) {
 		/* the entry exists, but it doesn't match the filter? */
+		rc = LDAP_NO_RESULTS_RETURNED;
 		goto cleanup;
 	}