unmake (a makefile linter)

unmake is a makefile linter emphasizing portability. It targets
the POSIX make standard. With unmake, you can develop practical,
portable makefile scripts, such as for provisioning dev environments.
No need for more heavyweight tools like Ansible, Docker, Lua, Python,
or WSL! Just good ol' make.

Note: older versions of rust-opt used /opt/rust/lib64 on x86_64 and
aarch64, but newer versions use /opt/rust/lib. If you see shared
library errors when this script runs, your rust-opt is outdated;
update it.