I wrote: 

>> So to me that means we can apply the patch below and be done with it.
>> Fine with you?
>
> No, I now think it shouldn't be changed, since the valgrind integration
> is supposed not to impose a significant speed penalty, and I can remove
> valgrind from the closure simply.  I'll send a new patch later.

Here it is, eventually, which gets rid of a lot from the closure.