Segfault when using Cat.flags.writeable = True

[MarcMassar]

Creating many times a multicat from Cat's who have flags.writeable = True cause a segfault.

The precise number of times you need to do this before it crashes is non-deterministic.

To preproduce the issue (with riptable version: 1.0.58):

import os
import sys

import riptable as rt
import numpy as np

print(f'{rt.__version__=}')

# We mute stderr as the loop below spams it with:
"""
Exception ignored in: <function Categorical.__del__ at 0x7f514934fe50>
Traceback (most recent call last):
  File ".../lib/python3.8/site-packages/riptable/rt_categorical.py", line 4473, in __del__
    del self._categories_wrap
AttributeError: _categories_wrap
"""
f = open(os.devnull, 'w')
sys.stderr = f



cat_len = 30
n_try = 10000

cat_1 = rt.Cat(np.arange(cat_len) % 10)
cat_2 = rt.Cat(np.arange(cat_len) % 11)

cat_1.flags.writeable = False

for _ in range(n_try):
    r = rt.Cat([cat_1, cat_2])

f.close()