message: Lower memory threshold for `parse_tensor_op_fuzz`
  This is needed because ASAN builds have additional checks with additional memory footprint so fuzzer that was at the borderline just below OOM threshold now OOMs.
diff: @@ -41,6 +41,8 @@ class FuzzParseTensor : public FuzzSession {
  // remainder of the fuzzer testing. Of course, this duplicates some work
  // but it's better than repeating the investigation whenever Autofuzz
  // detects another similar OOM.
  + // After adding `-fsanitize=null` to ASAN (cl/317376103), the memory
  + // footprint increased, so we lower the maximum threshold to 2^18.
  string as_string = string(reinterpret_cast<const char*>(data), size);
  TensorProto proto;
  if (!ParseProtoUnlimited(&proto, as_string)) {
  @@ -53,7 +55,7 @@ class FuzzParseTensor : public FuzzSession {
  }
  TensorShape shape(proto.tensor_shape());
  const int64 num_elements = shape.num_elements();
  - const int64 max_num_elements = 1 << 20;
  + const int64 max_num_elements = 1 << 18;
  if (num_elements > max_num_elements) {
  LOG(WARNING) << "Requiring a tensor with too many elements\n";
  return;
  