message: [XLA:GPU] Fix host conv checker canonicalization for f16 and nans.
  The GPU-side checker is correct, but the host-side checker was canonicalizing
  nan to F16_MAX.  The effect of this is that you'd get a "conv mismatch!" error
  but no description of exactly what mismatched.
diff: @@ -251,6 +251,9 @@ Status HostCompare(se::Stream* stream, se::DeviceMemoryBase lhs,
  const auto canonicalize = [](ComparisonType a) -> ComparisonType {
  if (std::is_same<ElementType, Eigen::half>::value && a) {
  constexpr float kMaxFp16Value = 65504.;
  + if (std::isnan(a)) {
  + return a;
  + }
  if (a < 0) {
  return -(kMaxFp16Value + 1);
  }
  