Change Squish to install MSVC11 to Windows 8.1

In Windows 8.1 the kernelmajversion is 6.3 so the current change is
needed for MSVC installation

Change-Id: Ic0f09fbd368208811d5e737a533e540522fe4735
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>
Reviewed-by: Tony Sarajärvi <tony.sarajarvi@digia.com>