TODO: improve transitive linking

[mszoek]

Currently, ld.lld will read the dependencies of a framework being linked to an app and link all of those dependencies to the app as well. This is intended to make commands like clang -o foo foo.m -framework AppKit work properly as they do on macOS - and it more or less does. The downside of this is that every app ends up with a long long list of link dependencies which can be seen with ldd. A better approach would be to move this into the runtime linker ld-elf so that apps only have dependencies on the frameworks they actually link.