Message 318037 - Python tracker

Note that I wouldn't call this issue absolutely specific to subinterpreters.  The "ownership" part is, but tracking the allocator has practical application under a single interpreter.  I suppose I could split this issue apart.  I lumped the two together because I expected the solution would be the same for both.  However, that's not necessarily the case.  Would it help to open a separate issue for tracking the allocator?