This is extra funny coming from musl which is expected to be used in cross compiling, embedded scenarios. If you want feature tests, add more versioned defines

This is extra funny coming from musl which is expected to be used in cross compiling, embedded scenarios. If you want feature tests, add more versioned defines not fewer in this case. You can actually version each public API if you want. Plus, inevitably you will hit a case that cannot be detected using reasonable tests (e.g. non-flaky).