build: Clarify the use of macOS specific flags

[jjerphan]

See:

• maint: Enable -Werror compiler flag for GCC, Clang and AppleClang #3611 (comment)
• https://github.com/conda-forge/micromamba-feedstock/blob/326c9d4b3f78189f48b00771388a15ef1528e031/recipe/build.sh#L10-L14

[mathbunnyru]

Thank you for finding where the wrong flags are added!

[mathbunnyru]

I will try to make it work: https://github.com/conda-forge/micromamba-feedstock/pull/225/files

[jjerphan]

Those flags are needed, but should be properly placed and documented in the appropriate CMakeLists.txt (I am not using macOS locally so I am not the best to understand and solve this issue).

See those past discussions: #3547 (comment)

[henryiii]

Why does this only come up in conda-forge, and not in the builds here or brew?

Where is kerberos being used? I don't see any usage of the API, it seems to only be coming in because it's manually linked as a .a file, so guessing it's a dependency of something else?

[jjerphan]

As often answers to those questions have to be discovered (looking at git histories).