runtime, x/sys/unix: Connectx is broken on darwin/amd64 [1.24 backport]

[gopherbot]

@randall77 requested issue #71302 to be considered for backport to the next 1.24 minor release.

Ok, that's good. I'll get that CL in soon.

I think the remaining question is, should we backport?
In favor:

1. This could cause really weird behavior and/or corruption on darwin/amd64. There is only one stdlib call affected (syscall/Getnameinfo), but several in x.sys (Connectx for freebsd, mmap for netbsd, dragonfly).
2. darwin/amd64 is a first-class port.

In opposition:

1. This has always been broken (since introduced in late 2022). It is not a regression from 1.24.
2. Only the Connectx failure has been noticed.

I'm leaning towards backporting. The fix is pretty simple and the unfixed behavior is very hard to debug and/or work around.

@gopherbot please open backport issues

[database64128]

Thanks for the backport request! I want to add that the only workaround for it is to use syscall.Syscall9 to make the underlying syscall directly, which is in itself a hack, and can break at any time, as these platforms do not provide a stable syscall interface.

[gopherbot]

Change https://go.dev/cl/665995 mentions this issue: [release-branch.go1.24] runtime: fix 9-arg syscall on darwin/amd64

[gopherbot]

Closed by merging CL 665995 (commit 43130af) to release-branch.go1.24.