make SparseSolverBase and IterativeSolverBase move constructable

Eigen/src/IterativeLinearSolvers/IterativeSolverBase.h

@@ -188,6 +188,9 @@ public:
     compute(matrix());
   }
 
+
+  IterativeSolverBase(IterativeSolverBase&&) = default;
+
   ~IterativeSolverBase() {}
 
   /** Initializes the iterative solver for the sparsity pattern of the matrix \a A for further solving \c Ax=b problems.