Add option to build embedd broker as shared library

[NorbertHeusser]

Thank you for contributing your time to the Mosquitto project!

Before you go any further, please note that we cannot accept contributions if
you haven't signed the Eclipse Contributor Agreement.
If you aren't able to do that, or just don't want to, please describe your bug
fix/feature change in an issue. For simple bug fixes it is can be just as easy
for us to be told about the problem and then go fix it directly.

Then please check the following list of things we ask for in your pull request:

• Have you signed the Eclipse Contributor Agreement, using the same email address as you used in your commits?
• Do each of your commits have a "Signed-off-by" line, with the correct email address? Use "git commit -s" to generate this line for you.
• If you are contributing a new feature, is your work based off the develop branch?
• If you are contributing a bugfix, is your work based off the fixes branch?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you successfully run make test with your changes locally?

---

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.62%. Comparing base (3c1a8c1) to head (9886279).
Report is 23 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3057      +/-   ##
===========================================
+ Coverage    81.35%   81.62%   +0.26%     
===========================================
  Files          191      196       +5     
  Lines        31780    32163     +383     
===========================================
+ Hits         25855    26253     +398     
+ Misses        5925     5910      -15     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[RimonGazi]

Could you kindly provide an update on when this feature is expected to be merged and available?

[NorbertHeusser]

Right now some builds are failing and I have to rebase the branch to the latest development branch before it maybe merged.
Will take a look, if I can find some time in the next days to update this PR.

As the PR is targeting the develop branch it will get into official broker packages anyway some time in the future. As I needed the change in one of my private projects I back ported the changes to the current 2.0.20 version. If you need a version like this you may pick the source from my fork: https://github.com/NorbertHeusser/mosquitto/releases/tag/v2.0.20-embedd-broker.

If there is an interest into this change in general I may try to make a different PR targeting the current master branch. But it's not my decision, if this change is considered a "fix" and maybe merged into the master branch.

[NorbertHeusser]

Updated the PR to the latest develop branch. Looks like the build issues are in the develop branch and not related to this change.

[RimonGazi]

Thanks for the update, @NorbertHeusser! I really appreciate the effort you've put into rebasing this to the latest develop branch. It's good to know that the build issues are related to the develop branch and not your changes.

Also, thank you for providing the link to the v2.0.20-embedded-broker release — that will definitely be helpful for anyone needing it before the feature is merged.

Looking forward to seeing this feature merged once the issues are resolved. Thanks again for your hard work and for keeping us updated!

[RimonGazi]

Hi @ralight, I appreciate all the work being done on this project! Could you provide an update on the status of this feature and whether there’s a timeline for its potential merge or release? Thanks in advance!