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

[Craig Topper via cfe-commits]

topperc wrote:

I'm concerned that llvm.assume is handled differently than a branch to unreachable in the middle end. Have you tested that these assumes have the intended effect?

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