Fix compilation of Qt Script with MSVC 2013.

Starting with MSVC 2013, more functions are provided.

Change-Id: Iabbc9a94e7ed01584baaa1bb17c06e41ac70830f
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>