Support new qnx targets

[jonathanpallant]

Description

Updates libc to support the newly renamed targets for QNX SDP 8

This PR largely involves adding target_os = "qnx" everywhere that said target_os = "nto", and replacing target_env = "nto800" with target_os = "qnx".

Plus there are some pthread mutex fixes, which we took from the our header files.

Sources

For QNX SDP 8.0:

$ grep "#define PTHREAD_MUTEX_INITIALIZER" /home/ubuntu/qnx800/target/qnx/usr/include/pthread.h -A1
#define PTHREAD_MUTEX_INITIALIZER                   \
	{ .__u = { .__count = _NTO_SYNC_NONRECURSIVE }, .__owner = _NTO_SYNC_MUTEX_FREE }
$ rg "#define _NTO_SYNC_NONRECURSIVE" /home/ubuntu/qnx800
/home/ubuntu/qnx800/target/qnx/usr/include/sys/target_nto.h
540:#define _NTO_SYNC_NONRECURSIVE	0x80000000U	/* mutexes */
$ rg "#define _NTO_SYNC_MUTEX_FREE" /home/ubuntu/qnx800
/home/ubuntu/qnx800/target/qnx/usr/include/sys/target_nto.h
550:#define _NTO_SYNC_MUTEX_FREE	0x00000000U	/*    0  newly-initialized mutex */

For QNX SDP 7.1:

$ grep "#define PTHREAD_MUTEX_INITIALIZER" /home/ubuntu/qnx710/target/qnx7/usr/include/pthread.h -A1
#define PTHREAD_MUTEX_INITIALIZER	\
	{ .__u = { .__count = (_NTO_SYNC_NONRECURSIVE | _NTO_SYNC_NODESTROY) }, .__owner = _NTO_SYNC_MUTEX_FREE }
$ rg "#define _NTO_SYNC_NONRECURSIVE" /home/ubuntu/qnx710
/home/ubuntu/qnx710/target/qnx7/usr/include/sys/target_nto.h
470:#define _NTO_SYNC_NONRECURSIVE	0x80000000U	/* mutexes */
$ rg "#define _NTO_SYNC_NODESTROY" /home/ubuntu/qnx710
/home/ubuntu/qnx710/target/qnx7/usr/include/sys/target_nto.h
476:#define _NTO_SYNC_NODESTROY		0x02000000U /* mutexes */
$ rg "#define _NTO_SYNC_MUTEX_FREE" /home/ubuntu/qnx710
/home/ubuntu/qnx710/target/qnx7/usr/include/sys/target_nto.h
479:#define _NTO_SYNC_MUTEX_FREE	0x00000000U	/*    0  mutexes, and old cond, sem, spin */

I don't have QNX SDP 7.0 available, so the old code path was left as-is.

Checklist

• Relevant tests in libc-test/semver have been updated (there are none)
• No placeholder or unstable values like *LAST or *MAX are
  included (see #3131)
• Tested locally (cd libc-test && cargo test --target mytarget);
  especially relevant for platforms that may not be checked in CI
  • These tests do not pass but they didn't pass before this PR either

@rustbot label +stable-nominated

[jonathanpallant]

Well this seems to fail because the copy of rustc used doesn't know about target_os = "qnx".

[tgross35]

If that's a new config only in nightly, you'll need to update this

View changes since the review

[rustbot]

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[rustbot]

⚠️ Warning ⚠️

• The following commits have merge commits (commits with multiple parents) in your changes. We have a no merge policy so these commits will need to be removed for this pull request to be merged.

  • 196df63

  You can start a rebase with the following commands:

  $ # rebase
  $ git pull --rebase https://github.com/rust-lang/libc.git main
  $ git push --force-with-lease
  

[jonathanpallant]

sigh. I clicked the "Merge changes from main" button, but the bot tells me I shouldn't have clicked the button. I'll rebase.

[tgross35]

I wish I could disable that button or make it rebase-only, unfortunately nothing we've tried can make it disappear

[jonathanpallant]

+ /usr/sbin/pkg_add curl
  pkg_add: Can't process [http://cdn.NetBSD.org:80/pub/pkgsrc/packages/NetBSD/x86_64/10.1/All//curl*:](http://cdn.netbsd.org/pub/pkgsrc/packages/NetBSD/x86_64/10.1/All//curl*:) 
  pkg_add: no pkg found for 'curl', sorry.

[tgross35]

LGTM, CI has been flaky so I'll try to merge later

View changes since this review