Fixes reordering in random ray. Refs openmc-dev#2997

include/openmc/random_ray/random_ray.h

@@ -34,18 +34,22 @@ class RandomRay : public Particle {
   static double distance_active_;        // Active ray length
   static unique_ptr<Source> ray_source_; // Starting source for ray sampling
 
+private:
+  int negroups_;
+
+public:
+
   //----------------------------------------------------------------------------
   // Public data members
   vector<float> angular_flux_;
 
   //----------------------------------------------------------------------------
   // Private data members
 private:
+  vector<float> delta_psi_;
   FlatSourceDomain* domain_ {nullptr}; // pointer to domain that has flat source
                                        // data needed for ray transport
-  vector<float> delta_psi_;
   double distance_travelled_ {0};
-  int negroups_;
   bool is_active_ {false};
   bool is_alive_ {true};
 }; // class RandomRay