Follow the stl standard: the default constructor of a shared_ptr creates a...

Follow the stl standard: the default constructor of a shared_ptr creates a NULL pointer, and does NOT allocate memory

[[Imported from SVN: r5654]]

dune/common/shared_ptr.hh

@@ -126,7 +126,7 @@ namespace Dune
   template<class T>
   inline shared_ptr<T>::shared_ptr()
   {
-    rep_ = new PointerRep;
+    rep_ = NULL;
   }
 
   template<class T>

dune/common/test/smartpointertest.cc

@@ -14,7 +14,7 @@ int main(){
   using namespace Dune;
   int ret=0;
   {
-    shared_ptr<double> b;
+    shared_ptr<double> b(new double(42.0));
     {
       shared_ptr<double> d(b);
       *b = 7;