PHP 5.4 compatibility

Changes for PHP 5.4 compatibility

Tested on

>PHP 5.4.15-1ubuntu3 (cli) (built: Jun 28 2013 17:41:13) 
Copyright (c) 1997-2013 The PHP Group
Zend Engine v2.4.0, Copyright (c) 1998-2013 Zend Technologies
    with Xdebug v2.2.3, Copyright (c) 2002-2013, by Derick Rethans

and

>PHP 5.3.10-1ubuntu3.6 with Suhosin-Patch (cli) (built: Mar 11 2013 14:31:48) 
Copyright (c) 1997-2012 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2012 Zend Technologies

One test fails on both versions before this patch is applied and after.

```=====================================================================
TIME START 2013-07-03 15:20:40
=====================================================================
PASS Check for jsonreader presence [tests/001.phpt] 
PASS Parse a simple short array [tests/002.phpt] 
PASS Parse a simple JSON object into an associative array [tests/003.phpt] 
PASS Parse some integers and floating-point numbers [tests/004.phpt] 
PASS parse a multi-dimentional JSON array and use the currentDepth property [tests/005.phpt] 
PASS Test that an error occurs when passing the maximal nesting level [tests/006.phpt] 
PASS Test that we can modify the max nesting level through an INI setting [tests/007.phpt] 
PASS Test that we can modify the max nesting level through a constructor attribute [tests/008.phpt] 
PASS Test that the constructor takes the right argument(s) [tests/009.phpt] 
PASS Check that the JSONReaderException class is available [tests/010.phpt] 
PASS Test that a warning is thrown in case of a JSON parse error [tests/011.phpt] 
PASS Test that an exception is thrown when ERRMODE_EXCEPT is set [tests/012.phpt] 
PASS Test that the value property is null for non-value tokens [tests/013.phpt] 
FAIL Test that we can get the current struct using currentStruct [tests/014.phpt] 
=====================================================================
TIME END 2013-07-03 15:20:41