[lld] [lld][RISCV] Add break to nested switch in `mergeAtomic` (PR #99762)

[Paul Kirth via llvm-commits]

ilovepi wrote:

> > Right, but I don’t recall seeing that with a pretty recent clang, and I want to know if you’re using gcc or another compiler so I know if I should see if we should fix that in clang.
> 
> Actually it's during compiling the `lld` itself lol~

Yes, but are you compiling with clang as the compiler or something else? Because if it’s clang then I don’t need to file a bug and try to run down why we’re not handling that. If you’re using something else, then I do. 

https://github.com/llvm/llvm-project/pull/99762