Add support for QNX Neutrino

[flba-eb]

See also https://github.com/rust-lang/rust/blob/57c215b08e18054c64428e00a291b45dc690d9de/library/std/src/sys/unix/os.rs#L64

[lambda-fairy]

Thanks for the PR!

Can you please add an entry to the changelog as well?

[flba-eb]

I've added a note to the [Unreleased] section; I can also move it to [0.3.2] if you release it today (or provide the release date).

[flba-eb]

Message of failing CI:

info: syncing channel updates for 'nightly-x86_64-apple-darwin'
info: update not yet available, sorry! try again later
error: toolchain 'nightly-x86_64-apple-darwin' is not installable
Error: Process completed with exit code 1.

I guess this is not related to my changes.

[lambda-fairy]

LGTM, thanks!

I can also move it to [0.3.2] if you release it today (or provide the release date).

I'll do that when I cut the release.