loplugin:unreffun

...of boost::sp_scalar_con-/destructor_hook overrides declared in
boost/smart_ptr/detail/sp_counted_impl.hpp

Change-Id: I5486dd890ef2ffdcb5973f3a8959ac0b6da376ee

slideshow/source/engine/sp_debug.cxx

@@ -32,6 +32,7 @@
 
 #include <boost/assert.hpp>
 #include <boost/detail/lightweight_mutex.hpp>
+#include <boost/shared_ptr.hpp>
 #include <canvas/debug.hxx>
 #include <cstdlib>
 #include <map>