[clang] [llvm] [clang][RISCV] Emit RISCV function-signature-based CFI label in llvm::Function metadata (PR #111661)

[Kito Cheng via cfe-commits]

kito-cheng wrote:

> I prefer to keep the function signature as an auxiliary metadata with the name riscv_lpad_func_sig, so future schemes and other language frontends can reuse the riscv_lpad_label metadata flow and have the opportunity of not being forced to adopt the idea of function signatures. 

My point is I would like to see the signature string in IR, so that sounds good to me.

https://github.com/llvm/llvm-project/pull/111661