Fixes for windows

Seems like a default constructor for KeyInfoEntry() is needed

gtsam/linear/IterativeSolver.h

@@ -104,6 +104,7 @@ namespace gtsam {
   class GTSAM_EXPORT KeyInfoEntry : public boost::tuple<size_t, size_t, size_t> {
   public:
     typedef boost::tuple<Key,size_t,Key> Base;
+	KeyInfoEntry(){}
     KeyInfoEntry(size_t idx, size_t d, Key start) : Base(idx, d, start) {}
     const size_t index() const { return this->get<0>(); }
     const size_t dim() const { return this->get<1>(); }

gtsam/linear/SubgraphPreconditioner.h

@@ -158,7 +158,7 @@ namespace gtsam {
     SubgraphBuilderParameters parameters_;
 
   private:
-    SubgraphBuilder() {}
+    SubgraphBuilder() {};
   };
 
   /*******************************************************************************************/