Debug: Allow inspecting non-GRF houses

src/table/newgrf_debug_data.h

@@ -509,7 +509,8 @@ static const NIVariable _niv_house[] = {
 };
 
 class NIHHouse : public NIHelper {
-	bool IsInspectable(uint index) const override        { return HouseSpec::Get(GetHouseType(index))->grf_prop.grffile != nullptr; }
+	bool IsInspectable(uint index) const override        { return true; }
+	bool ShowExtraInfoOnly(uint index) const override    { return HouseSpec::Get(GetHouseType(index))->grf_prop.grffile == nullptr; }
 	uint GetParent(uint index) const override            { return GetInspectWindowNumber(GSF_FAKE_TOWNS, GetTownIndex(index)); }
 	const void *GetInstance(uint index)const override    { return nullptr; }
 	const void *GetSpec(uint index) const override       { return HouseSpec::Get(GetHouseType(index)); }