[lld] [llvm] [LLVM] Use `reportFatalUsageError` for LTO usage errors (PR #140955)

[via llvm-commits]

bd1976bris wrote:

I was too quick to diagnose the issue. Whilst the `UNSUPPORTED` issue is present I checked and the test was being run when I tested on my dev setup before pushing. However, the failure is non-deterministic and and passed when I tested the patch before pushing.

https://github.com/llvm/llvm-project/pull/140955