Fix struct vs. class in forward declarations

src/mg_decoration.h

@@ -23,7 +23,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <set>
 #include "mapgen.h"
 
-class NoiseParams;
+struct NoiseParams;
 class Mapgen;
 class ManualMapVoxelManipulator;
 class PseudoRandom;

src/mg_ore.h

@@ -23,7 +23,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "util/string.h"
 #include "mapgen.h"
 
-class NoiseParams;
+struct NoiseParams;
 class Noise;
 class Mapgen;
 class ManualMapVoxelManipulator;

src/rollback.h

@@ -29,8 +29,8 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 class IGameDef;
 
-class ActionRow;
-class Entity;
+struct ActionRow;
+struct Entity;
 
 class RollbackManager: public IRollbackManager
 {

src/server.h

@@ -49,7 +49,7 @@ class Inventory;
 class Player;
 class PlayerSAO;
 class IRollbackManager;
-class RollbackAction;
+struct RollbackAction;
 class EmergeManager;
 class GameScripting;
 class ServerEnvironment;

src/wieldmesh.h

@@ -23,7 +23,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "irrlichttypes_extrabloated.h"
 #include <string>
 
-class ItemStack;
+struct ItemStack;
 class IGameDef;
 class ITextureSource;
 struct TileSpec;