Fix build and tests for uptime on OpenBSD

[lcheylus]

Fix #9157

Build for uptime OK on OpenBSD current/amd64 with Rust 1.90.0

$ cargo build -v --no-default-features --features uptime
(...)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 3.11s

$ ./target/debug/coreutils uptime
 10:58:57  up  7 days 22:44,  1 user,  load average: 0.21, 0.49, 0.75
$ ./target/debug/coreutils uptime -s
2025-10-29 12:14:06
$ ./target/debug/coreutils uptime && guptime
 10:59:30  up  7 days 22:45,  1 user,  load average: 0.25, 0.47, 0.73
 10:59:30  up 7 days 22:45,  1 user,  load average: 0.25, 0.47, 0.73

Tests for uptime OK on OpenBSD current/amd64 with Rust 1.90.0

$ cargo test -v --no-default-features --features uptime
(...)
running 7 tests
test test_uptime::test_invalid_arg ... ok
test test_uptime::test_uptime_check_users_openbsd ... ok
test test_uptime::test_uptime ... ok
test test_uptime::test_uptime_with_dir ... ok
test test_uptime::test_uptime_with_extra_argument ... ok
test test_uptime::test_uptime_with_non_existent_file ... ok
test test_uptime::test_uptime_since ... ok

test result: ok. 7 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.05s

[oech3]

@cakebaker Conflics with your #7256 ?

[cakebaker]

@oech3 it's possible, though my PR is work in progress anyway.

[codspeed-hq]

CodSpeed Performance Report

Merging #9158 will degrade performances by 2.55%

_{Comparing lcheylus:openbsd-uptime (7b1fbc0) with main (5b79ae4)}

Summary

❌ 1 regression
✅ 124 untouched

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
❌	du_human_balanced_tree[(5, 4, 10)]	10.1 ms	10.4 ms	-2.55%

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/tail/overlay-headers (fails in this run but passes in the 'main' branch)

[sylvestre]

Merci Laurent ! :)

[oech3]

Can this repo bump rust used at CI to 1.90+ from 1.85?

[cakebaker]

@oech3 in the CI we already use Rust stable for most jobs. What you probably mean is the MSRV (minimum supported Rust version), which currently is 1.85.0. Increasing this value is more "difficult" because other projects depend on this project. For example, ubuntu is switching to uutils coreutils and they use Rust 1.85.0 afaik. What's the reason you want to see a bump?

[oech3]

Because this issue(PR) and an issue is 1.90 specific and not detected by CI. (and newer ver uses fast linker by default.)

[lcheylus]

Because this issue(PR) and an issue is 1.90 specific and not detected by CI. (and newer ver uses fast linker by default.)

This error is not detected by CI because there is no CI for OpenBSD (work that's been in progress for a long time that I need to finish...).

[oech3]

Oops... Maybe, we can start CI from make UTILS="uptime true false"