Link OpenMP with modern CMake

[boxanm]

Leaving this draft here before I have time to finish it. Related links:
https://cliutils.gitlab.io/modern-cmake/chapters/packages/OpenMP.html
https://gist.github.com/scivision/16c2ca1dc250f54d34f1a1a35596f4a0
https://cmake.org/cmake/help/latest/module/FindOpenMP.html
https://gitlab.kitware.com/cmake/cmake/-/issues/24097

Note
This change requires 3.12.0 as a minimum CMake version.
Since Ubuntu 18.04 natively ships with CMake v3.10.2, this PR breaks an easy compilation on Bionic, although more recent CMake can be installed, just not with apt.

Description

Summary:

Changes and type of changes (quick overview):

---

Checklist:

Code related

• I have made corresponding changes to the documentation
  (i.e.: function, class, script header, README.md)
• I have commented hard-to-understand code
• I have added tests that prove my fix is effective or that my feature works
• All tests pass locally with my changes
  (Check README.md #Contributing
  for local testing procedure using libpointmatcher-build-system)

PR creation related

• My pull request base ref branch is set to the develop branch
  (the build-system won't be triggered otherwise)
• My pull request branch is up-to-date with the develop branch
  (the build-system will reject it otherwise)

PR description related

• I have included a quick summary of the changes
• I have indicated the related issue's id with # <issue-id> if changes are of type fix
• I have included a high-level list of changes and their corresponding type
  • Types: feat fix docs style refactor perf test build ci chore revert
  • Breaking changes: <type>!
  • Reference:
    see commit_msg_reference.md
    in the repository root for details

---

Note for repository admins

Release PR related

• Only repository admins have the privilege to push/merge on the default branch (ie: master)
  and the release branch.
• Keep PR in draft mode until all the release reviewers are ready to push the release.
• Once a PR from release -> master branch is created (not in draft mode),
  • it triggers the build-system test
  • (in-progress) and it triggers the semantic release automation

[sonarcloud]

Quality Gate passed

Kudos, no new issues were introduced!

0 New issues
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud