Code review comment for lp:~raof/mir/no-ipc-on-compositor-threads

Oh, dear.

This is now running into poor interactions with fork(); specifically:
Specifically:
       * After a fork() in a multithreaded program, the child can safely
          call only async-signal-safe functions (see signal-safety(7)) until
          such time as it calls execve(2).

When running “make test”, we've got a single process executing all the tests; since the ThreadExecutor is now static, we now have a thread waiting around before we get to fork().

This is why ptest doesn't fail; each test gets its own process...