Fix compatibility with libcxx 16 in boost 1.78 while using compilers used by old 1.78 builds

[traversaro]

This patch fixes #134 and conda-forge/libcxx-feedstock#114, by backporting boostorg/config#440 on 1.78 . This works as it is also on Boost 1.78 , as just defining BOOST_NO_CXX98_FUNCTION_BASE is ok as then std::unary_function is not used already in boost 1.78, see https://github.com/boostorg/container_hash/blob/boost-1.78.0/include/boost/container_hash/hash.hpp#L123-L133 .

Checklist

• Used a personal fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Reset the build number to 0 (if the version changed)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

[conda-forge-webservices]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[traversaro]

@conda-forge-admin, please rerender

[traversaro]

The PR is ready for review. @conda-forge/boost-cpp

[hmaarrfk]

I would like to have boost-cpp migrated to icu 72.

[ryanvolz]

I applied this compile definition manually in a build that depends on Boost and it did the job: conda-forge/gnuradio-feedstock#232. It would be really nice to have this merged soon though so it's not necessary to do the same for a bunch of downstream packages.

[ryanvolz]

Thanks @isuruf!

[traversaro]

Thanks a lot @isuruf!