Fix class/struct forward declaration inconsistencies (good on ya, MSVC)

Author: kahrl

src/script/common/c_content.h

@@ -39,19 +39,19 @@ extern "C" {
 #include "irrlichttypes_bloated.h"
 #include "util/string.h"
 
-class MapNode;
+struct MapNode;
 class INodeDefManager;
-class PointedThing;
-class ItemStack;
-class ItemDefinition;
-class ToolCapabilities;
-class ObjectProperties;
-class SimpleSoundSpec;
-class ServerSoundParams;
+struct PointedThing;
+struct ItemStack;
+struct ItemDefinition;
+struct ToolCapabilities;
+struct ObjectProperties;
+struct SimpleSoundSpec;
+struct ServerSoundParams;
 class Inventory;
-class NodeBox;
-class ContentFeatures;
-class TileDef;
+struct NodeBox;
+struct ContentFeatures;
+struct TileDef;
 class Server;
 struct DigParams;
 struct HitParams;

src/script/cpp_api/s_entity.h

@@ -23,8 +23,8 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "cpp_api/s_base.h"
 #include "irr_v3d.h"
 
-class ObjectProperties;
-class ToolCapabilities;
+struct ObjectProperties;
+struct ToolCapabilities;
 
 class ScriptApiEntity
 		: virtual public ScriptApiBase

src/script/cpp_api/s_inventory.h

@@ -22,7 +22,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include "cpp_api/s_base.h"
 
-class ItemStack;
+struct ItemStack;
 
 class ScriptApiDetached
 		: virtual public ScriptApiBase

src/script/cpp_api/s_item.h

@@ -23,10 +23,10 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "cpp_api/s_base.h"
 #include "irr_v3d.h"
 
-class PointedThing;
-class ItemStack;
+struct PointedThing;
+struct ItemStack;
 class ServerActiveObject;
-class ItemDefinition;
+struct ItemDefinition;
 class LuaItemStack;
 class ModApiItemMod;
 

src/script/cpp_api/s_node.h

@@ -26,7 +26,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "cpp_api/s_base.h"
 #include "cpp_api/s_nodemeta.h"
 
-class MapNode;
+struct MapNode;
 class ServerActiveObject;
 
 class ScriptApiNode

src/script/cpp_api/s_nodemeta.h

@@ -24,7 +24,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "cpp_api/s_item.h"
 #include "irr_v3d.h"
 
-class ItemStack;
+struct ItemStack;
 
 class ScriptApiNodemeta
 		: virtual public ScriptApiBase,