fix bug on count the deleted matching Statements

- the count is wrong because of overwriting the $filter variable and the wrong accessing of the $result variable
- if you use the subject, predicate and object for filter only the object will be filtered, because the filter of the subject and predicate was overwritten
- the second mistake is the accessing of the result array, counting the results with count($result) gives always 2 because the first level of the array is always setup with 'head' and 'result'. But to count the results statements you must count the bindings array ($result['results']['bindings'])