Improve tests for bug 67436

I always use a.php or b.php for local testing,
this diff makes the test more stable

Author: reeze

Zend/tests/bug67436/bug67436.phpt

@@ -9,7 +9,7 @@ error_reporting=
 
 spl_autoload_register(function($classname) {
 	if (in_array($classname, array('a','b','c'))) {
-		require_once ($classname . '.php');
+		require_once __DIR__ . "/{$classname}.php";
 	}
 });
 

Zend/tests/bug67436/bug67436_nohandler.phpt

@@ -9,7 +9,7 @@ error_reporting=-1
 
 spl_autoload_register(function($classname) {
 	if (in_array($classname, array('a','b','c'))) {
-		require_once ($classname . '.php');
+		require_once __DIR__ . "/{$classname}.php";
 	}
 });