Force usage of x64 registry on x64 systems from x86 builds
Force usage of x64 registry on x64 systems from x86 builds

Building an app for a x86 environment and running that app on an amd64 environment led to a `file not found` (aka failed to lookup relevant registry key) error. The added flag gets ignored on x86 systems, but will be followed on x64 systems.

fixes #2
denisbrodbeck/machineid