1.95 beta rustdoc regression: "unresolved imports `core::simd::LaneCount`, `core::simd::SupportedLaneCount`"

[theemathas]

Regression found by the 1.95 beta rustdoc crater run.

[INFO] [stdout] error[E0432]: unresolved imports `core::simd::LaneCount`, `core::simd::SupportedLaneCount`
[INFO] [stdout]   --> /opt/rustwide/cargo-home/registry/src/index.crates.io-1949cf8c6b5b557f/noise-functions-0.8.0/src/lookup_table.rs:21:36
[INFO] [stdout]    |
[INFO] [stdout] 21 |     use core::simd::{f32x2, f32x4, LaneCount, Simd, SupportedLaneCount};
[INFO] [stdout]    |                                    ^^^^^^^^^        ^^^^^^^^^^^^^^^^^^ no `SupportedLaneCount` in `simd`
[INFO] [stdout]    |                                    |
[INFO] [stdout]    |                                    no `LaneCount` in `simd`

(Other similar errors omitted.)

• https://crater-reports.s3.amazonaws.com/beta-1.95-rustdoc-2/1.95.0-beta.3/reg/noise-functions-config-0.10.0/log.txt
• https://crater-reports.s3.amazonaws.com/beta-1.95-rustdoc-2/1.95.0-beta.3/gh/LoganDark.stackblur-iter/log.txt
• https://crater-reports.s3.amazonaws.com/beta-1.95-rustdoc-2/1.95.0-beta.3/gh/bluurryy.noise-functions/log.txt
• https://crater-reports.s3.amazonaws.com/beta-1.95-rustdoc-2/1.95.0-beta.3/reg/fast-tlsh-0.1.10/log.txt
• https://crater-reports.s3.amazonaws.com/beta-1.95-rustdoc-2/1.95.0-beta.3/reg/noise-functions-0.8.2/log.txt
• https://crater-reports.s3.amazonaws.com/beta-1.95-rustdoc-2/1.95.0-beta.3/reg/stackblur-iter-0.2.0/log.txt

[fmease]

It's become apparent that under rustdoc, library features are not gated which enabled this issue:

• printf 'use std::simd::LaneCount;' | rustc +stable - --crate-type=lib → 1 (feature gate error)
• printf 'use std::simd::LaneCount;' | rustdoc +stable - --crate-type=lib → 0 (no feature gate error!)