I don't think it is a good idea to run the master branch on pypy, the `cpyext` module is said to be a lot slower (I have not used it either so I don't have any numbers) and most of the limitations for running on pypy now has nothing to do with the c-api, rather the bugs in numpy(py) so running using `cpyext` doesn't seem to have any advantage over `cffi` IMHO.

I think the only reason for putting them in `master` would be to minimize the difference outside the `_cl` (and `_pvt_struct`) module. However, as long as these changes doesn't make merging harder and are expected to be removed once the corresponding problem in `pypy` is solved (not sure how long it will take though..... the numpypy project seems to be moving slowly.... :( ), they may as well just live in the `cffi` branch.