fix for php5's more stringent type checking in foreach (auth/mysql.class.php)

as described at http://wiki.splitbrain.org/wiki:auth:mysql#using_mysql_5

darcs-hash:20060803231253-9b6ab-bbf06ef1e9141c5ec1d3c79dad7f88481296ad8b.gz

inc/auth/mysql.class.php

@@ -342,9 +342,11 @@ class auth_mysql extends auth_basic {
         $sql .= " ".$this->cnf['SortOrder']." LIMIT $first, $limit";
         $result = $this->_queryDB($sql);
 
-        foreach ($result as $user)
-          if (($info = $this->_getUserInfo($user['user'])))
-            $out[$user['user']] = $info;
+        if (!empty($result)) {
+          foreach ($result as $user)
+            if (($info = $this->_getUserInfo($user['user'])))
+              $out[$user['user']] = $info;
+        }
 
         $this->_unlockTables();
         $this->_closeDB();