fix SQL error in process.php

[GoogleCodeExporter]

a client (no system user) see the file list, but no file to download.

Cause is an incorrect SQL query:
SELECT * FROM tbl_files_relations WHERE (client_id="16" OR group_id IN 
("2,12,11,3")) AND file_id="38" AND hidden = "0"

shortened query: 
SELECT * FROM tbl_files_relations WHERE (client_id="16" OR group_id IN 
("2,12,11,3"))

results only files from group 2.

SELECT * FROM tbl_files_relations WHERE (client_id="16" OR group_id IN 
(2,12,11,3))
works fine

r561> diff process.php.orig process.php
75c75
<                               $files_own_query .= ' OR group_id IN ("' . $found_groups . '")';

---
>                               $files_own_query .= ' OR group_id IN (' . $found_groups . ')';

Original issue reported on code.google.com by r...@netbreaker.de on 3 May 2014 at 12:21