[llvm] [RISCV] Add support for new unprivileged extensions defined in profiles spec (PR #77458)

[Luke Lau via llvm-commits]

lukel97 wrote:

> I don't think so. It doesn't need to block this PR, but it would be good to raise the question about those implications in the profiles repo.

Filed https://github.com/riscv/riscv-profiles/issues/139

https://github.com/llvm/llvm-project/pull/77458