Musllinux

[mattip]

Closes #72

Also updates the multibuild subrepo to point to https://github.com/multi-build/multibuild, which means you need to run git submodule sync in your fork

[mattip]

The build is trying to use a manylinux_1_1_x86_64 docker image, which is wrong.

[mattip]

@liath do you see where the problem is with the musllinux stanza

[mattip]

Cool. We get a openblas64_-v0.3.19-22-g5188aede-musllinux_1_1_x86_64.tar.gz, openblas-v0.3.19-22-g5188aede-musllinux_1_1_x86_64.tar.gz, openblas-v0.3.19-22-g5188aede-musllinux_1_1_aarch64.tar.gz and openblas64_-v0.3.19-22-g5188aede-musllinux_1_1_aarch64.tar.gz, all built on musllinux docker images.

[liath]

Ah sorry, just noticed this. Looks like you got it sorted! Thanks :)