[lld] [llvm] [RISCV][MC] Reference ISA mapping symbols in R_RISCV_RELAX relocations (PR #201308)

[Kito Cheng via llvm-commits]

kito-cheng wrote:

> I'm happy with the implementation here.
> 
> I don't know if we've fully resolved the ABI proposal, but I hope having an LLVM implementation can get us there quickly :)

Yeah, it's not settle down yet, but seems like most people like this approach, we handled this proposal rather passively before since we don't really hit serious issue yet (ok, mostly can workaround via `.option norelax`), however it hit again and again recently on user code, that spend us lots time to debug...so we decide to fix this problem properly.

https://github.com/llvm/llvm-project/pull/201308