Make utils.addressof() work for raw userdata

docs/changelog.txt

@@ -58,6 +58,9 @@ changelog.txt uses a syntax similar to RST, with a few special sequences:
 - `buildingplan`: added Lua interface API
 - add item type param to dfhack.job.isSuitableMaterial() so the non_economic flag can be properly handled (it was being matched for all item types instead of just boulders)
 
+## Lua
+- ``utils.addressof()``: fixed for raw userdata
+
 # 0.47.04-r3
 
 ## New Plugins

library/lua/utils.lua

@@ -679,7 +679,7 @@ function df_expr_to_ref(expr)
 end
 
 function addressof(obj)
-    return select(2, obj:sizeof())
+    return select(2, df.sizeof(obj))
 end
 
 function OrderedTable()