Make test_PEAR_Dependency2::singleton() method static

Because it is called statically

Author: nikic

tests/download_test_classes.php.inc

@@ -525,8 +525,8 @@ class test_PEAR_Dependency2 extends PEAR_Dependency2
     var $_extensions;
     var $_installerVer;
 
-    function &singleton($config = null, $installoptions = null, $package = null,
-                              $state = PEAR_VALIDATE_INSTALLING)
+    static function &singleton($config = null, $installoptions = null, $package = null,
+                               $state = PEAR_VALIDATE_INSTALLING)
     {
         if (!isset($GLOBALS['_test_dep'])) {
             $GLOBALS['_test_dep'] = new test_PEAR_Dependency2($config,