Be compatible with PHP 5.3.*

Fix #20.

Author: weynhamz

buildPHAR.php

@@ -2,6 +2,24 @@
 
 $phar = new Phar('build/phpctags.phar', 0, 'phpctags.phar');
 
+if (version_compare(PHP_VERSION, '5.4.0') < 0) {
+    class RecursiveCallbackFilterIterator extends RecursiveFilterIterator {
+        public function __construct ( RecursiveIterator $iterator, $callback ) {
+            $this->callback = $callback;
+            parent::__construct($iterator);
+        }
+
+        public function accept () {
+            $callback = $this->callback;
+            return $callback(parent::current(), parent::key(), parent::getInnerIterator());
+        }
+
+        public function getChildren () {
+            return new self($this->getInnerIterator()->getChildren(), $this->callback);
+        }
+    }
+}
+
 $phar->buildFromIterator(
     new RecursiveIteratorIterator(
         new RecursiveCallbackFilterIterator(