Migrate `x86_64-fortanix-unknown-sgx-lvi` `run-make` test to rmake
Part of #121876 and the associated [Google Summer of Code project](https://blog.rust-lang.org/2024/05/01/gsoc-2024-selected-projects.html).
The final Makefile! Every Makefile test is now claimed.
This is difficult to test due to the uncommon architecture it is specific to. I don't think it is in the CI (I didn't find it in `jobs.yml`, but if there is a way to test it, please do.
Locally, on Linux, it compiles and panics at the `llvm_filecheck` part (if I replace the `x86_64-fortanix-unknown-sgx` with `x86_64-unknown-linux-gnu`, of course), which is expected.
For this reason, the Makefile and associated script have been kept, but with a leading underscore.
fe87433e8a