am 727f36c6: Merge change 4265 into donut

Merge commit '727f36c6a1c70ba5519ec9ce2da9ab1cf303a2ef'

* commit '727f36c6a1c70ba5519ec9ce2da9ab1cf303a2ef':
  process: Fix bug where if a thread exited while we were changing its control
  Fix the build: Remove ADD_SYSTEM_SERVICE, which I had accidentally