5e3032638e
Adding `erf` as unary and `powf` as binary. Same as `max(arg, 0.0)` for `ReLU`, `powf(arg, const)` can be either a generic (with broadcast) or a pair (`linalg.broadcast + linalg.powf`) and then lowered "correctly". Either way, the lower dialects need to know what kind of broadcast anyway, so no materialization of the constant tensors should remain. I want to flush the easy ones before we start working on type cast & softmax.