nsc: enable network simulation cradle

This adds the hooks to allow the nsc code to be compiled into ns-3 if
the --nsc flag is specified during 'waf configure'.

src/internet-stack/internet-stack.h

@@ -27,6 +27,7 @@ namespace ns3 {
 class Node;
 
 void AddInternetStack (Ptr<Node> node);
+void AddNscInternetStack (Ptr<Node> node, const std::string &soname);
 
 }//namespace ns3