[clang] [RISCV] Add canonical ISA string as Module metadata in IR. (PR #80760)

[Jessica Clarke via cfe-commits]

jrtc27 wrote:

> I just noticed we only set EF_RISCV_RVC based on C, and not Zca. Is that a bug?

I think so; binutils sets it for both.

https://github.com/llvm/llvm-project/pull/80760