fix memory leak in superlu backend

Eigen/src/Sparse/SuperLUSupport.h

diff --git a/Eigen/src/Sparse/SuperLUSupport.h b/Eigen/src/Sparse/SuperLUSupport.h
index cf0f802..6df94e3 100644
--- a/Eigen/src/Sparse/SuperLUSupport.h
+++ b/Eigen/src/Sparse/SuperLUSupport.h
@@ -287,6 +287,8 @@
 
     ~SparseLU()
     {
+      Destroy_SuperNode_Matrix(&m_sluL);
+      Destroy_CompCol_Matrix(&m_sluU);
     }
 
     inline const LMatrixType& matrixL() const