stabilize build system: depends, installer, boost/bdb fixes, cross targets groundwork

depends/x86_64-pc-linux-gnu/include/boost/signals2/trackable.hpp

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+// Boost.Signals2 library
+
+// Copyright Frank Mori Hess 2007,2009.
+// Copyright Timmo Stange 2007.
+// Copyright Douglas Gregor 2001-2004. Use, modification and
+// distribution is subject to the Boost Software License, Version
+// 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
+
+// Compatibility class to ease porting from the original
+// Boost.Signals library.  However,
+// boost::signals2::trackable is NOT thread-safe.
+
+// For more information, see http://www.boost.org
+
+#ifndef BOOST_SIGNALS2_TRACKABLE_HPP
+#define BOOST_SIGNALS2_TRACKABLE_HPP
+
+#include <boost/assert.hpp>
+#include <boost/shared_ptr.hpp>
+#include <boost/weak_ptr.hpp>
+
+namespace boost {
+  namespace signals2 {
+    namespace detail
+    {
+        class tracked_objects_visitor;
+        
+        // trackable_pointee is used to identify the tracked shared_ptr 
+        // originating from the signals2::trackable class.  These tracked
+        // shared_ptr are special in that we shouldn't bother to
+        // increment their use count during signal invocation, since
+        // they don't actually control the lifetime of the
+        // signals2::trackable object they are associated with.
+        class trackable_pointee
+        {};
+    }
+    class trackable {
+    protected:
+      trackable(): _tracked_ptr(static_cast<detail::trackable_pointee*>(0)) {}
+      trackable(const trackable &): _tracked_ptr(static_cast<detail::trackable_pointee*>(0)) {}
+      trackable& operator=(const trackable &)
+      {
+          return *this;
+      }
+      ~trackable() {}
+    private:
+      friend class detail::tracked_objects_visitor;
+      weak_ptr<detail::trackable_pointee> get_weak_ptr() const
+      {
+          return _tracked_ptr;
+      }
+
+      shared_ptr<detail::trackable_pointee> _tracked_ptr;
+    };
+  } // end namespace signals2
+} // end namespace boost
+
+#endif // BOOST_SIGNALS2_TRACKABLE_HPP