Another compilation fix with ICC/MSVC combo

Eigen/src/SparseCore/SparseBlock.h

diff --git a/Eigen/src/SparseCore/SparseBlock.h b/Eigen/src/SparseCore/SparseBlock.h
index b6a2d23..16a20a5 100644
--- a/Eigen/src/SparseCore/SparseBlock.h
+++ b/Eigen/src/SparseCore/SparseBlock.h
@@ -393,6 +393,8 @@
   protected:
     friend class InnerIterator;
     friend class ReverseInnerIterator;
+    
+    EIGEN_INHERIT_ASSIGNMENT_OPERATORS(BlockImpl)
 
     typename XprType::Nested m_matrix;
     const internal::variable_if_dynamic<Index, XprType::RowsAtCompileTime == 1 ? 0 : Dynamic> m_startRow;