Codechange: Suppress warnings when asserts are disabled (#8917)

src/industry_cmd.cpp

@@ -2140,6 +2140,7 @@ static Industry *CreateNewIndustry(TileIndex tile, IndustryType type, IndustryAv
 	Industry *i = nullptr;
 	size_t layout_index = RandomRange((uint32)indspec->layouts.size());
 	CommandCost ret = CreateNewIndustryHelper(tile, type, DC_EXEC, indspec, layout_index, seed, GB(seed2, 0, 16), OWNER_NONE, creation_type, &i);
+	(void)ret; // assert only
 	assert(i != nullptr || ret.Failed());
 	return i;
 }