A crash happened on mod_destroy() due to librdkafka thrd_join(), in case of multiple restarts, in case of ssl kafka connection.

Init kafka only for timer and routing processes. Add checks for rk pointer.

<!-- Kamailio Pull Request Template -->

<!-- IMPORTANT: - for detailed contributing guidelines, read: https://github.com/kamailio/kamailio/blob/master/.github/CONTRIBUTING.md - pull requests must be done to master branch, unless they are backports of fixes from master branch to a stable branch - backports to stable branches must be done with 'git cherry-pick -x ...' - code is contributed under BSD for core and main components (tm, sl, auth, tls) - code is contributed GPLv2 or a compatible license for the other components - GPL code is contributed with OpenSSL licensing exception -->

#### Pre-Submission Checklist <!-- Go over all points below, and after creating the PR, tick all the checkboxes that apply --> <!-- All points should be verified, otherwise, read the CONTRIBUTING guidelines from above--> <!-- If you're unsure about any of these, don't hesitate to ask on sr-dev mailing list --> - [X] Commit message has the format required by CONTRIBUTING guide - [X] Commits are split per component (core, individual modules, libs, utils, ...) - [X] Each component has a single commit (if not, squash them into one commit) - [X] No commits to README files for modules (changes must be done to docbook files in `doc/` subfolder, the README file is autogenerated)

#### Type Of Change - [X] Small bug fix (non-breaking change which fixes an issue) - [ ] New feature (non-breaking change which adds new functionality) - [ ] Breaking change (fix or feature that would change existing functionality)

#### Checklist: <!-- Go over all points below, and after creating the PR, tick the checkboxes that apply --> - [ ] PR should be backported to stable branches - [X] Tested changes locally - [ ] Related to issue #XXXX (replace XXXX with an open issue number)

#### Description <!-- Describe your changes in detail -->

You can view, comment on, or merge this pull request online at:

https://github.com/kamailio/kamailio/pull/4147

-- Commit Summary --

* kafka: Fix mod_destroy() crash

-- File Changes --

M src/modules/kafka/kafka_mod.c (9) M src/modules/kafka/kfk.c (95)

-- Patch Links --

https://github.com/kamailio/kamailio/pull/4147.patch https://github.com/kamailio/kamailio/pull/4147.diff