issue 11457: add Windows SDK 8.1 library search path to sc.ini

The 8.1 SDK has a different path to the library folder again. This often bytes Win64 users.

It should be fixed for the 2.065 release. @eco: Does anything need to be done to the installer, too?

https://d.puremagic.com/issues/show_bug.cgi?id=11457