Do not compile examples automatically
When the dune-functions module is build via dunecontrol
(or some user module that depends on it), all examples are also compiled. Every single one of them is a full Dune simulation and hence takes some time to compile.
Though this might not have too high priority, I find it unnecessary when I'm using a header-only module like dune-functions to wait for examples being compiled that I'm not interested in running.