[cleanup][SphereGrid] fix dgf parser constructor.

dune/grid/spheregrid/dgfparser.hh

@@ -29,9 +29,9 @@ namespace Dune
     : dgfHostFactory_( input, comm ),
       grid_( 0 )
     {
-      HostGrid *hostGrid = dgfHostFactory_.grid();
-      assert( hostGrid != 0 );
-      grid_ = new Grid( *hostGrid );
+      std::shared_ptr< HostGrid > hostGrid( dgfHostFactory_.grid() );
+      assert( hostGrid );
+      grid_ = new Grid( hostGrid );
     }
 
     explicit DGFGridFactory ( const std::string &filename,
@@ -41,7 +41,6 @@ namespace Dune
     {
       std::shared_ptr< HostGrid > hostGrid( dgfHostFactory_.grid() );
       assert( hostGrid );
-      std::ifstream input( filename.c_str() );
       grid_ = new Grid( hostGrid );
     }