message: Avoid final-dtor-non-final-class warning.
  On an out of tree build with clang-11, the following warning was generated:
  ```
  note: mark 'mlir::TF::TensorFlowDialect' as 'final' to silence this warning
  class TensorFlowDialect : public Dialect {
  ^
  1 error generated.
  ```
diff: @@ -28,7 +28,7 @@ namespace TF {
  class ResourceType;
  class VariantType;
  -class TensorFlowDialect : public Dialect {
  +class TensorFlowDialect final : public Dialect {
  public:
  explicit TensorFlowDialect(MLIRContext *context);
  