Link the kernel using LLD #96
Description
The new "linker-flavor" field added to target.json files rust-lang/rust#40018 should make it possible to use LLD rather than GCC as a linker. It would be nice to use LLD, since it's cross-platform and would mean that we no longer depend on x86_64-elf-binutils. This would also allow us to cross-compile for more platforms than x86_64-pc-elf without needing to add more cross toolchains to our dependencies.