www/privoxy: Update to 3.0.33 stable

This update fixes a couple of security issues. Quoting the ChangeLog:

• Security/Reliability:
  • cgi_error_no_template(): Encode the template name to prevent XSS (cross-side scripting) when Privoxy is configured to servce the user-manual itself. Commit 0e668e9409c. OVE-20211102-0001. CVE-2021-44543. Reported by: Artem Ivanov
  • get_url_spec_param(): Free memory of compiled pattern spec before bailing. Reported by Joshua Rogers (Opera) who also provided the fix. Commit 652b4b7cb0. OVE-20211201-0003. CVE-2021-44540.
  • process_encrypted_request_headers(): Free header memory when failing to get the request destination. Reported by Joshua Rogers (Opera) who also provided the fix. Commit 0509c58045. OVE-20211201-0002. CVE-2021-44541.
  • send_http_request(): Prevent memory leaks when handling errors Reported by Joshua Rogers (Opera) who also provided the fix. Commit c48d1d6d08. OVE-20211201-0001. CVE-2021-44542.

The complete list of changes is available at:
https://lists.privoxy.org/pipermail/privoxy-announce/2021-December/000009.html

PR: 260290
MFH: 2021Q4
Security: 897e1962-5d5a-11ec-a3ed-040e3c3cf7e7
(cherry picked from commit dec093e215760204b994f01511820348f21cf1be)