`Location` vs `Link-Location` issues

The current state is that the tool doing the lookup needs to know what platform it is running for to know if it needs to point at `Link-Location` or `Location`, since on Windows you do not link with the `.dll`, but with the interface library, pointed at by `Link-Location`. On all other platforms you will link with the `.so` or `.dylib`, pointed at by by `Location`. This is especially burdensome when cross compiling, since now the tool needs to know what platform it going to be running *for*, not just on.

We can avoid all of this ambiguity by doing one of two things:
1. Location should point to the library you will ink with, the implementation library on Windows, the shared object elsewhere
2. whenever `Location` is provided `Link-Location` should also be provided, and point to the actual thing to link to, as above