musl upstream is down

[udoprog]

Seems like https://git.musl-libc.org/git/musl is down (504 Bad Gateway), meaning building this project from git no longer works.

I'm not sure how to contact the musl project, so I'm opening an issue here for now since this is the project which breaks for me.

It might be an idea to host a mirror of the project on GitHub with the commit being depended on.