work around pypy ctypes incompatibility
work around pypy ctypes incompatibility

The following works with cpython, but not with pypy:

    import ctypes
    class Test:
      def __init__(self, value):
        self._as_parameter_ = value
    ctypes.cast(Test(0), ctypes.POINTER(ctypes.c_int64))

CVerhoosel/nutils,joostvanzwieten/nutils,wijnandhoitinga/nutils,nutils/nutils