Use separate directory in dit_004.phpt

Make sure the directory is not modified while we're iterating it,
which may give unstable results.

Author: nikic

ext/spl/tests/dit_004.phpt

@@ -2,7 +2,13 @@
 SPL: DirectoryIterator and clone
 --FILE--
 <?php
-$a = new DirectoryIterator(__DIR__);
+
+@mkdir($dir = __DIR__ . '/dit_004');
+touch($dir . '/file1');
+touch($dir . '/file2');
+touch($dir . '/file3');
+
+$a = new DirectoryIterator($dir);
 $b = clone $a;
 var_dump((string)$b == (string)$a);
 var_dump($a->key(), $b->key());
@@ -13,6 +19,14 @@ $c = clone $a;
 var_dump((string)$c == (string)$a);
 var_dump($a->key(), $c->key());
 ?>
+--CLEAN--
+<?php
+$dir = __DIR__ . '/dit_004';
+unlink($dir . '/file1');
+unlink($dir . '/file2');
+unlink($dir . '/file3');
+rmdir($dir);
+?>
 --EXPECT--
 bool(true)
 int(0)