Remove irr namespace (#16309)

irr/include/IBillboardSceneNode.h

@@ -6,8 +6,6 @@
 
 #include "ISceneNode.h"
 
-namespace irr
-{
 namespace scene
 {
 class ICameraSceneNode;
@@ -72,7 +70,7 @@ public:
 		So we don't know the real boundingboxes before that. Which would be too late for culling.
 		That is why the usual getBoundingBox will return a "safe" boundingbox which is guaranteed
 		to contain the billboard. While this function can return the real one. */
-	virtual const core::aabbox3d<f32> &getTransformedBillboardBoundingBox(const irr::scene::ICameraSceneNode *camera) = 0;
+	virtual const core::aabbox3d<f32> &getTransformedBillboardBoundingBox(const scene::ICameraSceneNode *camera) = 0;
 
 	//! Get the amount of mesh buffers.
 	/** \return Amount of mesh buffers (IMeshBuffer) in this mesh. */
@@ -87,4 +85,3 @@ public:
 };
 
 } // end namespace scene
-} // end namespace irr