Tsan Dependencies Not Getting Traced Through Threadqueues

[insertinterestingnamehere]

Due to some fundamental limitations of thread sanitizer's implementation it's not able to trace the happens-before relationships through our threadqueues reliably. I suspect this is causing most (if not all) of the remaining thread sanitizer failures. The fix for this will be some kind of extension of #249 to provide more information to the santitizer to get it working properly.

[insertinterestingnamehere]

I'm closing the other tsan-related issues since they'll all need to be re-triaged after this one's fixed. Most of what's still showing up now is buggy behaviour and/or false positives caused by the incomplete interop with thread sanitizer.