hpy: support for reversed slots
I was able to run piconumpy benchmarks with a recent PyPy 3.7 nightly build. It's not yet possible to build the universal extension with PyPy but I guess it's going to be possible when the branch hpy-0.0.2 will be merged again in py3.7. Anyway, because the universal extension can be build with CPython, it can be already be used with PyPy.
Some piconumpy tests fail with PyPy whereas they pass with CPython.
piconumpy.array, one can do
a * 2 but not
2 * a. The error is
TypeError: unsupported operand type(s) for *: 'int' and 'array'.
@antocuni wrote that this is because reversed slots are not fully supported by the PyPy version.