nir/lower_idiv: add new llvm-based path
This ports over the AMDGPU LLVM backend's lowering of division, modulo and remainer operations as a new path in nir_lower_idiv(). This new path is used by ACO.
This ports over the AMDGPU LLVM backend's lowering of division, modulo and remainer operations as a new path in nir_lower_idiv(). This new path is used by ACO.