vectorization interface causes Alberta regression

Originally posted by @felix.gruber in !121 (merged):

@joe: this merge broke dune-grid with Alberta. Somehow the new swap(T& v1, T& v2, bool mask) prevents std::swap(T& v1, T& v2) to be found.

The error message I get with g++-5.2.0 is

/home/data/gruber/src/dune-git/dune-grid/dune/grid/albertagrid/elementinfo.hh:391:11: error: no matching function for call to ‘swap(Dune::Alberta::ElementInfo<1>::Instance*&, Dune::Alberta::ElementInfo<1>::Instance*&)’
       swap( instance_, other.instance_ );
           ^
In file included from /home/data/gruber/src/dune-git/dune-common/dune/common/densematrix.hh:19:0,
                 from /home/data/gruber/src/dune-git/dune-common/dune/common/fmatrix.hh:15,
                 from /home/data/gruber/src/dune-git/dune-grid/dune/grid/albertagrid/agrid.hh:25,
                 from /home/data/gruber/src/dune-git/dune-grid/dune/grid/albertagrid.hh:5,
                 from /home/data/gruber/src/dune-git/dune-grid/dune/grid/albertagrid/dgfparser.hh:8,
                 from /home/data/gruber/src/dune-git/dune-grid/dune/grid/albertagrid/dgfparser.cc:10:
/home/data/gruber/src/dune-git/dune-common/dune/common/simd.hh:300:8: note: candidate: template<class T> void Dune::swap(T&, T&, bool)
   void swap(T &v1, T &v2, bool mask)
        ^
/home/data/gruber/src/dune-git/dune-common/dune/common/simd.hh:300:8: note:   template argument deduction/substitution failed:
In file included from /home/data/gruber/src/dune-git/dune-grid/dune/grid/albertagrid/meshpointer.hh:15:0,
                 from /home/data/gruber/src/dune-git/dune-grid/dune/grid/albertagrid/coordcache.hh:6,
                 from /home/data/gruber/src/dune-git/dune-grid/dune/grid/albertagrid/agrid.hh:42,
                 from /home/data/gruber/src/dune-git/dune-grid/dune/grid/albertagrid.hh:5,
                 from /home/data/gruber/src/dune-git/dune-grid/dune/grid/albertagrid/dgfparser.hh:8,
                 from /home/data/gruber/src/dune-git/dune-grid/dune/grid/albertagrid/dgfparser.cc:10:
/home/data/gruber/src/dune-git/dune-grid/dune/grid/albertagrid/elementinfo.hh:391:11: note:   candidate expects 3 arguments, 2 provided
       swap( instance_, other.instance_ );
           ^

and looking at the code in dune/grid/albertagrid/elementinfo.hh:391

    template< int dim >
    inline ElementInfo< dim >::ElementInfo ( ElementInfo &&other )
      : instance_( NULL )
    {
      using namespace std;
      swap( instance_, other.instance_ );
    }

I do not understand why std::swap isn't used, especially since <utility> gets included at the top of the file so that it's definition should be available for overload resolution.