Do not use ClassVars with generic variables - #6348

>>> from ctypes import pointer
>>> pointer._type_
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'builtin_function_or_method' object has no attribute '_type_'

>>> from ctypes import c_int
>>> i = c_int(1)
>>> pointer(i)._type_
<class 'ctypes.c_int'>

>>> from ctypes import Array
>>> Array._type_
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: type object '_ctypes.Array' has no attribute '_type_'

>>> from ctypes import *
>>> class POINT(Structure):
...   _fields_ = ("x", c_int), ("y", c_int)
... 
>>> Arr = POINT * 3
>>> Arr._type_
<class '__main__.POINT'>
>>> Arr._length_
3
>>> type(Arr)
<class '_ctypes.PyCArrayType'>
>>> Arr
<class '__main__.POINT_Array_3'>