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

[Jessica Clarke via llvm-commits]

jrtc27 wrote:

> @jrtc27 Do you have thoughts on this change w.r.t. the defaults? I recall you had expressed concerns previously in the psABI, so I want to be sure we're changing the status quo appropriately.

To be clear, without reading the patch in detail, this is making the default be A6S? I don't think I have concerns with that other than to note that transitioning from A6S to A7 will be an ABI break for existing binaries, so the timeline for when that's ok to do is unclear.

https://github.com/llvm/llvm-project/pull/84597