Fix warning. Initialization order in Sumoperator.

dune/solvers/operators/sumoperator.hh

@@ -33,8 +33,8 @@ class SumOperator
         //! construct from summands
         SumOperator(double a, SparseMatrixType& A, double b, LowRankMatrixType& M):
             alpha_(a),
-            sparse_matrix_(&A),
             beta_(b),
+            sparse_matrix_(&A),
             lowrank_matrix_(&M),
             summands_allocated_internally_(false)
         {}
@@ -42,8 +42,8 @@ class SumOperator
         //! construct from summands
         SumOperator(SparseMatrixType& A, LowRankMatrixType& M):
             alpha_(1.0),
-            sparse_matrix_(&A),
             beta_(1.0),
+            sparse_matrix_(&A),
             lowrank_matrix_(&M),
             summands_allocated_internally_(false)
         {}