Removed compiler warnings.

git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/trunk@4436 178a84e3-b1eb-0310-8ba1-8eac791a3b58

src/robots/default_robot.hpp

@@ -28,7 +28,14 @@
 class Track;
 class LinearWorld;
 class QuadGraph;
-class irr::scene::ISceneNode;
+
+namespace irr
+{
+    namespace scene
+    {
+        class ISceneNode;
+    }
+}
 
 class DefaultRobot : public AutoKart
 {

src/robots/new_ai.hpp

@@ -27,7 +27,13 @@
 class Track;
 class LinearWorld;
 class QuadGraph;
-class irr::scene::ISceneNode;
+namespace irr
+{
+    namespace scene
+    {
+        class ISceneNode;
+    }
+}
 
 class NewAI : public AutoKart
 {