The last musl update we had was many years ago: #4813.

There are many fixes and improvements in upstream musl that we would like to include. We should also find better ways to track our local changes and pull in new upstream releases.

Significant work has already been done in preparation for the upgrade including:

• Creation of a fork to hold emscripten-specific changes to upstream musl: https://github.com/emscripten-core/musl. The current set of changes can be seen here: emscripten-core/musl@v1.1.15...emscripten_2.0.12
• Script for importing musl changes: Add musl update script. NFC. #13269