install x86 vcredist only if it is necessary

Change-Id: I7d3b3aa35ceef3502c6b4250b60a572631a117be
Reviewed-by: Kai Koehne <kai.koehne@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>
Reviewed-by: Tim Jenssen <tim.jenssen@digia.com>