Update Eigen to: https://gitlab.com/libeigen/eigen/commit/4217a9f09018b1eb3ce800919a69c7c3df47f9cb

PiperOrigin-RevId: 288797909
Change-Id: I3f4e9027bb320c8b4add73b1fbbf2a4877ab5e8a
diff --git a/Eigen/src/Core/CwiseUnaryView.h b/Eigen/src/Core/CwiseUnaryView.h
index 21cf5ea..ff3134d 100644
--- a/Eigen/src/Core/CwiseUnaryView.h
+++ b/Eigen/src/Core/CwiseUnaryView.h
@@ -121,6 +121,8 @@
     {
       return derived().nestedExpression().outerStride() * sizeof(typename internal::traits<MatrixType>::Scalar) / sizeof(Scalar);
     }
+  protected:
+    EIGEN_DEFAULT_EMPTY_CONSTRUCTOR_AND_DESTRUCTOR(CwiseUnaryViewImpl)
 };
 
 } // end namespace Eigen