Use uname() for OS version string on FreeBSD. Note possible implementation for Android. Return a specific platform name when on any platform `#if os()` knows about that doesn't have a more specialized implementation.
Use uname() for OS version string on FreeBSD. Note possible implementation for Android. Return a specific platform name when on any platform `#if os()` knows about that doesn't have a more specialized implementation.

apple/swift-corelibs-foundation,apple/swift-corelibs-foundation,apple/swift-corelibs-foundation,apple/swift-corelibs-foundation,apple/swift-corelibs-foundation