[lld] [llvm] Reapply "[RISCV] Support RISCV Atomics ABI attributes (#84597)" (PR #90266)

[Paul Kirth via llvm-commits]

ilovepi wrote:

> Since we're going to have the flag emission under a flag anyways, can we separate the LLD part into a separate review? Doing so would seem to unblock the compiler side changes, and let the LLD review comments move at their own pace.

Done. LLD support is in https://github.com/llvm/llvm-project/pull/97347

https://github.com/llvm/llvm-project/pull/90266