Feature request: musl detection on linux

`musl` becomes more and more popular. Projects with native library component require to detect platform and musl in order to ship proper package.

I kindly ask to add a simple API which detects musl. An example of use case:
```
... classifier: osdetector.classifier + (osdetector.ismusl ? "-musl" : "")
```

musl detection is pretty simple:
```
# ls -la /proc/self/map_files/ | grep musl
lr-------- 1 root root 64 Dec 18 22:17 7fcd2900f000-7fcd29023000 -> /lib/ld-musl-x86_64.so.1
...
```

You can see how gradle does it: https://github.com/gradle/gradle/pull/28258

Thanks