ca-certificates: fix python3-cryptography woes in certdata2pem.py

This patch is a revert of the upstream patch to Debian's ca-certificate
commit 033d52259172 ("mozilla/certdata2pem.py: print a warning for expired certificates.")

The reason is, that this change broke builds with the popular
Ubuntu 20.04 LTS (focal) releases which are shipping with an
older version of the python3-cryptography package that is not
compatible.

|Traceback (most recent call last):
|  File "certdata2pem.py", line 125, in <module>
|    cert = x509.load_der_x509_certificate(obj['CKA_VALUE'])
|TypeError: load_der_x509_certificate() missing 1 required positional argument: 'backend'
|make[5]: *** [Makefile:6: all] Error 1

...or if the python3-cryptography was missing all together:
|Traceback (most recent call last):
|  File "/certdata2pem.py", line 31, in <module>
|    from cryptography import x509
|ModuleNotFoundError: No module named 'cryptography'

More concerns were raised by Jo-Philipp Wich:
"We don't want the build to depend on the local system time anyway.
Right now it seems to be just a warning but I could imagine that
eventually certs are simply omitted of found to be expired at
build time which would break reproducibility."

Link: <https://github.com/openwrt/openwrt/commit/7c99085bd697>
Reported-by: Chen Minqiang <ptpt52@gmail.com>
Reported-by: Shane Synan <digitalcircuit36939@gmail.com>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
(cherry picked from commit 25bc66eb40)

package/system/ca-certificates/patches/0001-ca-certificates-fix-python3-cryptography-woes-in-cer.patch

@@ -0,0 +1,53 @@
+From 3c51cb5ff1d0db41fb3288fb555c7e7055cf3e86 Mon Sep 17 00:00:00 2001
+From: Christian Lamparter <chunkeey@gmail.com>
+Date: Wed, 1 Dec 2021 14:41:31 +0100
+Subject: [PATCH] ca-certificates: fix python3-cryptography woes in
+ certdata2pem.py
+
+reverts the code portion of the Debian's ca-certificate
+commit 033d52259172 ("mozilla/certdata2pem.py: print a warning for expired certificates.")
+
+It broke builds with the popular Ubuntu 20.04 (focal) releases.
+This was due to them shipping with an older python3-cryptography
+version which is not compatible.
+
+More concerns were raised by jow- as well:
+"We don't want the build to depend on the local system time anyway."
+
+Reported-by: Chen Minqiang <ptpt52@gmail.com>
+Reported-by: Shane Synan <digitalcircuit36939@gmail.com>
+Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
+---
+--- a/work/mozilla/certdata2pem.py
++++ b/work/mozilla/certdata2pem.py
+@@ -21,16 +21,12 @@
+ # USA.
+ 
+ import base64
+-import datetime
+ import os.path
+ import re
+ import sys
+ import textwrap
+ import io
+ 
+-from cryptography import x509
+-
+-
+ objects = []
+ 
+ # Dirty file parser.
+@@ -121,13 +117,6 @@ for obj in objects:
+     if obj['CKA_CLASS'] == 'CKO_CERTIFICATE':
+         if not obj['CKA_LABEL'] in trust or not trust[obj['CKA_LABEL']]:
+             continue
+-
+-        cert = x509.load_der_x509_certificate(obj['CKA_VALUE'])
+-        if cert.not_valid_after < datetime.datetime.now():
+-            print('!'*74)
+-            print('Trusted but expired certificate found: %s' % obj['CKA_LABEL'])
+-            print('!'*74)
+-
+         bname = obj['CKA_LABEL'][1:-1].replace('/', '_')\
+                                       .replace(' ', '_')\
+                                       .replace('(', '=')\