Remove irr namespace (#16309)

irr/src/CGLTFMeshFileLoader.cpp

@@ -30,8 +30,6 @@
 #include <variant>
 #include <vector>
 
-namespace irr {
-
 /* Notes on the coordinate system.
  *
  * glTF uses a right-handed coordinate system where +Z is the
@@ -920,5 +918,3 @@ tiniergltf::GlTF SelfType::parseGLTF(io::IReadFile* file)
 }
 
 } // namespace scene
-
-} // namespace irr