Do an Alpha NT 3.50 build

[davidrg]

As the NT 3.50 SDK includes the compiler. Worthwhile checking Alpha support is still working even if it won't be a fully featured build

[davidrg]

The compiler in the NT 3.50 SDK can build CKW just fine, but the linker is broken - you have to use the linker from Visual C++ 4.0 instead.