Code review comment for lp:~alan-griffiths/mir/use-compare_exchange_weak-correctly

(1) 3rd_party/android-deps/std/atomic.h: I think it's probably a better idea to not fix 3rd party code when there is nothing provably wrong with the current form (yet). We should assume Google's using it in a way that is safe until proven otherwise. Or is it definitely not safe right now?

Happy for our own code to get fixes though...