add support for chimera linux

[jabuxas]

chimera linux is a musl llvm distro.
website is https://chimera-linux.org/
target is:

clang version 18.1.8
Target: x86_64-chimera-linux-musl
Thread model: posix
InstalledDir: /usr/bin

i encountered a problem trying to install texlab, texlab-x86_64-alpine.tar.gz seems to work fine, but there's no musl target in the registry to use.