Fix types on XDR::xdr_ops function struct for clang16 compilation

[hmacdope]

Fixes #4397

Changes made in this Pull Request:

• Changes struct function signatures to match stricter type checking on function pointers in Clang16:
• https://releases.llvm.org/16.0.0/tools/clang/docs/ReleaseNotes.html

PR Checklist

• [NA] Tests?
• [NA] Docs?
• CHANGELOG updated?
• Issue raised/referenced?

Developers certificate of origin

• I certify that this contribution is covered by the LGPLv2.1+ license as defined in our LICENSE and adheres to the Developer Certificate of Origin.

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📚 Documentation preview 📚: https://mdanalysis--4408.org.readthedocs.build/en/4408/

[github-actions]

Linter Bot Results:

Hi @hmacdope! Thanks for making this PR. We linted your code and found the following:

There are currently no issues detected! 🎉

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (b9f321c) 93.41% compared to head (86614e0) 93.41%.

Additional details and impacted files

@@            Coverage Diff             @@
##           develop    #4408     +/-   ##
==========================================
  Coverage    93.41%   93.41%             
==========================================
  Files          171      185     +14     
  Lines        22511    23625   +1114     
  Branches      4129     4129             
==========================================
+ Hits         21028    22069   +1041     
- Misses         963     1036     +73     
  Partials       520      520             

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[IAlibay]

I don't think there are action or azure runners with clang-16 by default for testing. If we think it's worth it, it might be possible to do compilation tests by directly installing clang-16.

[hmacdope]

@IAlibay I have tested this locally, and have setup a test directly on feedstock with conda-forge/mdanalysis-feedstock#65, is that sufficent for this PR?

I don't think there are action or azure runners with clang-16 by default for testing. If we think it's worth it, it might be possible to do compilation tests by directly installing clang-16.

Is this aimed at this PR or more as a general integration test for the CI suite?

[IAlibay]

Is this aimed at this PR or more as a general integration test for the CI suite?

I'm not sure, this is obviously something that has caught us out. Last time I tried to do a compiler sweep things didn't go super well, so maybe not the best place to put efforts in.

[hmacdope]

The build using this patch and clang16 infra on feedstock seems to work fine. conda-forge/mdanalysis-feedstock#65

[IAlibay]

cheers, lgtm assuming tests (edit: i.e. beyond compile with clang-16) ran fine locally!