[llvm] [RISCV] Select and/or/xor with certain constants to Zbb ANDN/ORN/XNOR (PR #120221)

[Sam Elliott via llvm-commits]

https://github.com/lenary approved this pull request.

I'm happy with this.

By default, LLVM will squash-merge, so can you pre-commit the new test file before landing this?

https://github.com/llvm/llvm-project/pull/120221