[clang] [llvm] [RISCV][LLVM] Enable atomics for 'Zalrsc' (PR #163672)

[Sam Elliott via llvm-commits]

lenary wrote:

I'm not going to manage to review this PR this week. Once the other reviewers are happy, don't block waiting for me to look at this in depth.

https://github.com/llvm/llvm-project/pull/163672