[amg] allocate coarse grid solver using a rebound vector allocator

this is necessary to ensure that the solver fulfills the alignement
requirements of the vector

dune/istl/paamg/amg.hh

@@ -512,15 +512,32 @@ namespace Dune
           {
             if(matrices_->matrices().coarsest().getRedistributed().getmat().N()>0)
               // We are still participating on this level
+
+              // we have to allocate these types using the rebound allocator
+              // in order to ensure that we fulfill the alignement requirements
+#warning alignment
               solver_.reset(new BiCGSTABSolver<X>(const_cast<M&>(matrices_->matrices().coarsest().getRedistributed()),
                                                   *scalarProduct_,
                                                   *coarseSmoother_, 1E-2, 1000, 0));
             else
               solver_.reset();
           }else
-            solver_.reset(new BiCGSTABSolver<X>(const_cast<M&>(*matrices_->matrices().coarsest()),
-                                                *scalarProduct_,
-                                                *coarseSmoother_, 1E-2, 1000, 0));
+          {
+            // we have to allocate these types using the rebound allocator
+            // in order to ensure that we fulfill the alignement requirements
+            using Alloc = typename A::template rebind<BiCGSTABSolver<X>>::other;
+            Alloc alloc;
+            auto p = alloc.allocate(1);
+            alloc.construct(p,
+              const_cast<M&>(*matrices_->matrices().coarsest()),
+              *scalarProduct_,
+              *coarseSmoother_, 1E-2, 1000, 0);
+            solver_.reset(p,[](BiCGSTABSolver<X>* p){
+                Alloc alloc;
+                alloc.destroy(p);
+                alloc.deallocate(p,1);
+              });
+          }
         }
       }