[Bug] SuspendApp freezes app on System.exit

```kotlin
import arrow.continuations.SuspendApp

fun main(args: Array) =
SuspendApp {
System.exit(1)
}
```

This main completely freezes the process, needing an external `SIGKILL` to stop.

Maybe I'm doing something wrong, and also I realize that `System.exit` inside SuspendApp's passed-in closure may be a bad idea, but this isn't necessarily under the user's control.