build: rename and gate systemd_logind configuration

[xtqqczze]

Rename the feat_systemd_logind feature to systemd_logind.

Prevent systemd_logind code from being enabled on unsupported platforms, improving cross-platform compilation and bringing the workspace closer to supporting:

cargo check -q --workspace --all-targets --all-features --target x86_64-pc-windows-gnu

[oech3]

We remove it at #11579 .

[github-actions]

Binary size comparison:

Individual binary size comparison VS main (threshold: >=5% AND >=4 KB).

Total size of compared binaries: 148.57 MB (+972 KB, +0.64%)

Significant per-binary changes:
  ls         2.11 MB ->    3.25 MB  (+1.14 MB, +54.36%)
  mkfifo     1.16 MB ->    1.08 MB  (-76 KB, -6.42%)
  mknod      1.16 MB ->    1.09 MB  (-76 KB, -6.38%)
  mkdir      1.16 MB ->    1.09 MB  (-72 KB, -6.04%)

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/date/resolution (fails in this run but passes in the 'main' branch)

[codspeed]

Merging this PR will regress 7 benchmarks

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 7 improved benchmarks
❌ 7 regressed benchmarks
✅ 377 untouched benchmarks
⏩ 62 skipped benchmarks¹

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	five_38_bit_primes	1.5 s	1.8 s	-16.61%
❌	Simulation	expand_many_lines[100000]	95 ms	106.2 ms	-10.53%
❌	Simulation	tsort_complex_dag[50000]	87.6 ms	97.2 ms	-9.79%
❌	Simulation	expand_custom_tabstops[50000]	26.9 ms	29.6 ms	-9.27%
❌	Simulation	tsort_tree_dag[(10, 3)]	36.5 ms	39.4 ms	-7.34%
❌	Simulation	tsort_wide_dag[100000]	157.6 ms	167 ms	-5.64%
❌	Simulation	tsort_linear_chain[1000000]	1.9 s	2 s	-4.75%
⚡	Simulation	three_39_bit_primes	901.6 ms	378.6 ms	×2.4
⚡	Simulation	join_french_locale	26.7 ms	24 ms	+11.09%
⚡	Simulation	join_full_match	26.7 ms	24 ms	+11.08%
⚡	Simulation	join_partial_overlap	22.1 ms	20.4 ms	+8.36%
⚡	Simulation	join_unicode_locale	2.6 ms	2.4 ms	+6.65%
⚡	Simulation	join_custom_separator	25.9 ms	24.4 ms	+6.08%
⚡	Simulation	rm_recursive_tree	14.4 ms	13.7 ms	+5.28%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing xtqqczze:feat_systemd_logind (f986fd3) with main (fe26d56)²}

Footnotes

1. 62 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

2. No successful run was found on main (a5bc606) during the generation of this report, so fe26d56 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[oech3]

I think systemd is better if it can be renamed. But I prefer #11579 .

[xtqqczze]

@sylvestre Regardless of whether #11579 is desirable (and I think it probably is), I still think we should merge this in the meantime. The merge conflicts should be straightforward to resolve.

[xtqqczze]

@sylvestre Could you merge this please; I have changes depending on this.

[xtqqczze]

@sylvestre ready

[oech3]

I like --features systemd for the case someone started using libsystemd.so much more (and shorter name).

[xtqqczze]

I like --features systemd for the case someone started using libsystemd.so much more (and shorter name).

Currently we are not using general libsystemd functionality; just the systemd-logind subsystem. So it is shorter, but potentially misleading because it suggests broader integration than actually exists.

[oech3]

It is not matter since we use openssl instead of openssl_api_name for cksum.

[xtqqczze]

It is not matter since we use openssl instead of openssl_api_name for cksum.

I think we have a feature named openssl to match the crate name, rather than anything particularly well considered.