[clang] [llvm] [cmake] Add config for riscv(32|64)-unknown-elf (PR #176353)

[Jessica Clarke via cfe-commits]

jrtc27 wrote:

> the inclusion of LLVMExports relies on the target system supporting shared libraries

But you're building the compiler for the host, not the target, so why does that matter?

https://github.com/llvm/llvm-project/pull/176353