[PATCH] Workaround ASAN race condition in future tests by manually joining threads.

[Jonathan Roelofs]

So 4 things:
  *  I'm a little out of my comfort zone with this thread stuff... pretty far from my area of expertise
  *  Perhaps you missed a few, for example: thread/futures/futures.promise/set_value_at_thread_exit_void.pass.cpp (grep for 'detach' in tests).
  *  Doesn't this reduce the test coverage for the thread.detach() method?
  *  I *really* *really* don't like the idea of changing tests to push bugs under the rug. It'd be much better to 'XFAIL: asan' these. I have a thought on how to fix asan that I'll add to the PR.


Cheers,

Jon

http://reviews.llvm.org/D6347