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

[Luke Lau via llvm-commits]

lukel97 wrote:

Hi, I'm seeing a segfault with GNU ld after this when running clang with `-march=rv64g` and riscv64-linux-gnu-ld 2.42. With LLD 18.1.3 I get a warning:
```
ld.lld: warning: /var/folders/yl/qbdtspsx7t97vqcl6dm6q9540000gn/T/--4b08f5.o:(.riscv.attributes): invalid tag 0xe at offset 0x45
```

I haven't tried it with a ToT lld yet but I thought I'd flag this in case something was accidentally made backwards incompatible!

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