Code review comment for lp://staging/~alan-griffiths/miral/fix-1668651

Note that on versions of Mir prior to 0.24 closing the server with a signal (e.g. SIGTERM) still leads to a segfault. That's because we lack mir::server::add_stop_callback() - or any way to hook into that mechanism for closing the server.

That affects 16.04LTS (Mir 0.21) but is "only" a crash on exit. I don't think we need to block. (But I'll think about possible solutions.)