Add some headers for g++-4.4.

src/display.hpp

@@ -48,6 +48,8 @@ class arrow;
 #include "video.hpp"
 #include "widgets/button.hpp"
 
+#include <list>
+
 #include <boost/function.hpp>
 #include <boost/scoped_ptr.hpp>
 

src/side_filter.hpp

@@ -23,6 +23,8 @@ class unit;
 class unit_map;
 class team;
 
+#include <set>
+
 //side_filter: a class that implements the Standard Side Filter
 class side_filter {
 public: