Laurence Tratt

Via Ted Unangst, Darwin [also skips negative fds in poll](https://github.com/apple/darwin-xnu/blob/main/bsd/kern/sys_generic.c#L1886) and, interestingly, has this comment in the code: ``` /* per spec, ignore fd values below zero */ ```

@SteveLauC If one can avoid the extra `Vec` that would be cool. FWIW I have (but currently untested while I change the program that would call this!) locally: ```diff diff...

Thank you @SteveLauC -- much appreciated!