Make itemdef.h safe to include anywhere

src/CMakeLists.txt

@@ -396,12 +396,14 @@ set(independent_SRCS
 	gettext_plural_form.cpp
 	httpfetch.cpp
 	hud.cpp
+	inventory.cpp
 	itemstackmetadata.cpp
 	lighting.cpp
 	log.cpp
 	metadata.cpp
 	modchannels.cpp
 	nameidmapping.cpp
+	nodemetadata.cpp
 	nodetimer.cpp
 	noise.cpp
 	objdef.cpp
@@ -429,7 +431,6 @@ set(common_SRCS
 	environment.cpp
 	filesys.cpp
 	gettext.cpp
-	inventory.cpp
 	inventorymanager.cpp
 	itemdef.cpp
 	light.cpp
@@ -440,7 +441,6 @@ set(common_SRCS
 	mapnode.cpp
 	mapsector.cpp
 	nodedef.cpp
-	nodemetadata.cpp
 	pathfinder.cpp
 	player.cpp
 	porting.cpp