This is the same as CFFI's create modulename except we don't include the
    CFFI version.

def _create_modulename(cdef_sources, source, sys_version):
    """
    This is the same as CFFI's create modulename except we don't include the
    CFFI version.
    """
    key = '\x00'.join([sys_version[:3], source, cdef_sources])
    key = key.encode('utf-8')
    k1 = hex(binascii.crc32(key[0::2]) & 0xffffffff)
    k1 = k1.lstrip('0x').rstrip('L')
    k2 = hex(binascii.crc32(key[1::2]) & 0xffffffff)
    k2 = k2.lstrip('0').rstrip('L')
    return '_xprintidle_cffi_{0}{1}'.format(k1, k2)