Code review comment for lp:~alan-griffiths/mir/fix-1415321

Still not wild on deliberately exporting C++ symobls from mirclient, and not wild about exporting implementation details from mirclient.

I don't think this is the right way to fix the bug, but I don't particularly feel like fixing it the right way myself at the moment, and this isn't going to make it any harder should I later choose to :).