ioctl: add support for cygwin

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What does this PR do

Enable ioctl support for Cygwin, based on the Cygwin C headers

Checklist:

• I have read CONTRIBUTING.md
• I have written necessary tests and rustdoc comments
• A change log has been added if this PR modifies nix's API

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I was going to unpin and update libc because it is needed for downstream projects, but it seems to need a pending fix in libc. Will wait for it before trying again.

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Cleaning up commits.

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Seems like most platforms compile fine, it's libc itself that's failing to build for those platforms?

[oech3]

#2715 (comment)

@tgross35 Similar missing issue like rust-lang/libc#4913 ?

[tgross35]

NetBSD: the target was pretty broken, we used that as an opportunity to do some minor breakage in https://github.com/rust-lang/libc/releases/tag/0.2.178. The special casing here will need to be removed

nix/src/sys/event.rs

Lines 94 to 97 in ba63e90

	#[cfg(any(freebsdlike, apple_targets, target_os = "openbsd"))]
	type type_of_udata = *mut libc::c_void;
	#[cfg(target_os = "netbsd")]
	type type_of_udata = intptr_t;

and #2709 for IFF_NOTRAILERS.

uclibc: Looks like this was unintentional from rust-lang/libc@2fe1d91.

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Maybe the libc fixes should be split off into a different PR? Or combined into #2709?

Anyways, cleaned up commits for now.

[oech3]

Does not this repo have bot for crate bump?

[tgross35]

For uclibc, rust-lang/libc@3dad489 and rust-lang/libc@e0ed72d. I'll cut a new release tomorrowish.

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I'll cut a new release tomorrowish.

No 0.2 backport?

[tgross35]

What do you mean?

[oech3]

I think backport means 0.2.180 (no major bump). Sorry for triggering too many release (stty, musl ,etc...

[tgross35]

I don't usually do the backports until just before I release. I have it cooking locally but just haven't had a chance to wrap it up yet.

Sorry for triggering too many release (stty, musl ,etc...

Certainly nobody's fault 🙂 the past two releases have been ~10kloc which is way higher than the average of around 1-3k, so there were some things that snuck in.

I'll ping on this thread when the release is out.

[tgross35]

It's out https://github.com/rust-lang/libc/releases/tag/0.2.180