fix: optimization: PVS-Studio warning V802

Rearranged structure fields in decreasing order of size to reduce structure size from 32 to 24 and 12 to 8 bytes on 64-bit platforms.

Reported by: PVS-Studio
Signed-off-by: Vyacheslav Ivanov <islavaivanov76@gmail.com>

src/items/ItemDef.hpp

@@ -38,8 +38,8 @@ struct ItemDef {
 
     struct {
         itemid_t id;
-        item_funcs_set funcsset {};
         blockid_t placingBlock;
+        item_funcs_set funcsset {};
         bool emissive = false;
     } rt {};