Function copy_no_return

sources/covscript.cpp:179–187

	std::size_t struct_builder::mCount = 0;

	void copy_no_return(var &val)
	{
		if (!val.is_rvalue()) {
			val.clone();
			val.detach();
		}
		else
			val.mark_trivial();
	}

	var copy(var val)
	{