User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:38.0) Gecko/20100101 Thunderbird/38.7.1
Why reduce the number of people who could use Csmith?
Why? Because modernizing our code makes it nicer to work with and
perhaps more likely to be maintained going forward. It's not as if
we're selling a product here!