Adding a RAII class to promote an object containt a symbol to be dlopened with RTLD_GLOBAL

[Iximiel]

Description

As we were discussing, I modified @GiovanniBussi's class to fit into plumed, with warnings.

I also reverted the changes from #985, since DLLoader::EnsureGlobalDLOpen makes using RTLD_GLOBAL more granular.

For example, on linux, an embedded python interpreter needs its .so to be loaded with RTLD_GLOBAL, for importing compiled modules, with this you can make only libPython*.so GLOBAL, and not the other part of the code that rely on it.

I am using DLLoader as a namespace for EnsureGlobalDLOpen.

Target release

I would like my code to appear in release 2.10

Type of contribution

• changes to code or doc authored by PLUMED developers, or additions of code in the core or within the default modules
• changes to a module not authored by you
• new module contribution or edit of a module authored by you

Copyright

• I agree to transfer the copyright of the code I have written to the PLUMED developers or to the author of the code I am modifying.

• the module I added or modified contains a COPYRIGHT file with the correct license information. Code should be released under an open source license. I also used the command cd src && ./header.sh mymodulename in order to make sure the headers of the module are correct.

Tests

• I added a new regtest or modified an existing regtest to validate my changes.
• I verified that all regtests are passed successfully on GitHub Actions.

[codecov-commenter]

Codecov Report

Attention: 8 lines in your changes are missing coverage. Please review.

Comparison is base (91d56cb) 84.10% compared to head (b81cac6) 84.06%.

❗ Current head b81cac6 differs from pull request most recent head 7d301b4. Consider uploading reports for the commit 7d301b4 to get more accurate results

Files	Patch %	Lines
src/tools/DLLoader.cpp	20.00%	8 Missing ⚠️

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@                 Coverage Diff                 @@
##           autoconf-dladdr    #1000      +/-   ##
===================================================
- Coverage            84.10%   84.06%   -0.04%     
===================================================
  Files                  602      602              
  Lines                56231    56233       +2     
===================================================
- Hits                 47292    47272      -20     
- Misses                8939     8961      +22     

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