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

[Piotr Fusik via llvm-commits]

https://github.com/pfusik commented:

Added Zbs testing. Added `andimm64` test. Squashed the change so that the effect on tests is clear.

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