Make the allocator compile even if variadic templates are activated.

BTW: Currently they are not at all activated in dune-common.

[[Imported from SVN: r7069]]

dune/common/debugallocator.hh

@@ -277,7 +277,7 @@ namespace Dune
     template<typename ... _Args>
     void construct(pointer p, _Args&&... __args)
     {
-      ::new((void *)p)_Tp(std::forward<_Args>(__args) ...);
+      ::new((void *)p)T(std::forward<_Args>(__args) ...);
     }
 #endif
     //! destroy an object of type T (i.e. call the Destructor)

dune/common/mallocallocator.hh

@@ -80,7 +80,7 @@ namespace Dune
     template<typename ... _Args>
     void construct(pointer p, _Args&&... __args)
     {
-      ::new((void *)p)_Tp(std::forward<_Args>(__args) ...);
+      ::new((void *)p)T(std::forward<_Args>(__args) ...);
     }
 #endif
     //! destroy an object of type T (i.e. call the Destructor)