[clang] [Clang][RISCV] Add assumptions to vsetvli/vsetvlimax (PR #79975)

[Wang Pengcheng via cfe-commits]

wangpc-pp wrote:

After some random thinking, I think these assumptions may need to be added to vsetvli/vsetvlimax LLVM intrinsics instead of adding them in Clang CodeGen. In this way, we can make other frontends like `flang/Rust/TVM/MLIR/...` benefit from these assumptions. Is it possible? I don't see a way to add similar attributes to intrinsics.

https://github.com/llvm/llvm-project/pull/79975