[ANGLE] Fix compilation with MSVC2013 Update4

Update4 provides a native Sleep implementation. Hence the wrapper
needs to be disabled.

Change-Id: I162da45934b02c262ac09b557c66c3363c276e54
Reviewed-by: Kai Koehne <kai.koehne@theqtcompany.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>
Reviewed-by: Oliver Wolff <oliver.wolff@theqtcompany.com>