Add glibc extensions for posix_spawn*.

[kosayoda]

This PR adds support for posix spawn extensions implemented by glibc: https://elixir.bootlin.com/glibc/glibc-2.37.9000/source/posix/spawn.h#L201.

[rustbot]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @JohnTitor (or someone else) soon.

Please see the contribution instructions for more information.

[JohnTitor]

@bors r+

[bors]

📌 Commit 2c46c2a has been approved by JohnTitor

It is now in the queue for this repository.

[bors]

⌛ Testing commit 2c46c2a with merge e717704...

[bors]

💔 Test failed - checks-actions

[kosayoda]

As far as I can tell, the sparc64-unknown-linux-gnu test is failing because it's using an older version of glibc?

[JohnTitor]

As far as I can tell, the sparc64-unknown-linux-gnu test is failing because it's using an older version of glibc?

Yes:

libc/ci/docker/sparc64-unknown-linux-gnu/Dockerfile

Lines 1 to 2 in 90531f6

	# FIXME: Update to 22.04 once Debian image of sparc64 has a newer glibc.
	FROM ubuntu:20.04

You could skip tests for that arch by tweaking libc-test's build.rs.

[JohnTitor]

@bors r+

[bors]

📌 Commit fb7d1c5 has been approved by JohnTitor

It is now in the queue for this repository.

[bors]

⌛ Testing commit fb7d1c5 with merge 5e98ea3...

[bors]

☀️ Test successful - checks-actions, checks-cirrus-freebsd-12, checks-cirrus-freebsd-13, checks-cirrus-freebsd-14
Approved by: JohnTitor
Pushing 5e98ea3 to master...

[bors]

☀️ Test successful - checks-actions, checks-cirrus-freebsd-12, checks-cirrus-freebsd-13, checks-cirrus-freebsd-14
Approved by: JohnTitor
Pushing 5e98ea3 to master...

[bors]

👀 Test was successful, but fast-forwarding failed: 422 Changes must be made through a pull request.