Threading issues (raised by --sanitize=thread)

[liscio]

When I run the ConsoleKit tests with the thread sanitizer on, there are a few races that need to be cleaned up.

I noticed this while validating my own tools that rely on heavy multithreading, and the ActivityIndicator was giving me grief, and making it hard to find my own issues.

To reproduce this, just try the following at the command-line:

swift test --sanitize=thread

PR incoming…