>All I need to know is what version of Musl I am dealing with and I can
>configure myself.

Are you willing to maintain an #ifdef forest for all the versions of
all the libcs and all the kernels your programs may be used with, so
you can list exhaustively the available features in every configuration?

At the risk of jumping in on a question asked of someone else: yes, absolutely! (Not _all_ available features of course, just the ones required.)

There are generally not that many nonstandard features you'd want to use in a typical program, and using an ifdef forest to implement an abstraction layer around those couple items is just fine.