[clang] [llvm] [RISCV] Implement shadow stack on shadow stack mode with Zicfiss. (PR #68075)

[Paul Kirth via cfe-commits]

ilovepi wrote:

The title should probably be changed to something like:

`[RISCV] Add Zicfiss support to the shadow call stack implementation`

The current title doesn't make much sense to me, but maybe I've misunderstood the intent?

https://github.com/llvm/llvm-project/pull/68075