message: Allow tuple as results of mhlo.custom_call op (NFC)
diff: @@ -1471,12 +1471,12 @@ def HLO_CustomCallOp: HLO_Op<"custom_call", []> {
  See https://www.tensorflow.org/xla/operation_semantics#customcall.
  }];
  let arguments = (ins
  - Variadic<HLO_Tensor>:$args,
  + Variadic<HLO_TensorOrTuple>:$args,
  StrAttr:$call_target_name,
  DefaultValuedAttr<BoolAttr, "false">:$has_side_effect,
  DefaultValuedAttr<StrAttr, "">:$backend_config
  );
  - let results = (outs Variadic<HLO_Tensor>);
  + let results = (outs Variadic<HLO_TensorOrTuple>);
  let hasCustomHLOConverter = 1;
  }
  