I think this code is getting L0, not L1 cache size, if I'm reading the Intel manual right. (I might not be.) Either way, the code comment and the printed message should match, whichever way is right. :)

`#[thread_local]` allows us to maintain a per-thread list of destructors. This also avoids the need to synchronize global data (which is particularly tricky within the TLS callback function).

After updating the minimum required LLVM version to 12 we can use
apple-a14 as that is closer in features to the Apple M1 than the A12.
Once the minimum required LLVM version is updated to 13 we can use
apple-m1.

Make printed message match the code comment

I think this code is getting L0, not L1 cache size, if I'm reading the Intel manual right. (I might not be.) Either way, the code comment and the printed message should match, whichever way is right. :)

…ocs, r=Mark-Simulacrum

Document clippy on nightly-rustc

Adding Clippy's docs to nightly-rustc, based on commit 01cf0bd. This PR only adds `clippy_utils` to the documentation. I've decided to only document one crate for now, as `clippy_lints` etc. contain very specific and undocumented functions which aren't really reusable. I'm guessing that they would mostly clutter up the search results with little benefit.

`./x.py --stage 1 doc src/tools/clippy` if working fine now after the help that `````@jyn514````` and `````@ehuss````` have provided. A big THANK YOU to them!

…chton

Windows thread-local keyless drop

`#[thread_local]` allows us to maintain a per-thread list of destructors. This also avoids the need to synchronize global data (which is particularly tricky within the TLS callback function).

r? ```@alexcrichton```

Use apple-a14 as target CPU for aarch64-apple-darwin

After updating the minimum required LLVM version to 12 (rust-lang#90175) we can use `apple-a14` as target CPU, because that CPU is similar in features to the Apple M1 (see [LLVM 13 source](https://github.com/llvm/llvm-project/blob/b8016b626ec7095c7d57ebfffb2135dc5c3077b8/llvm/lib/Target/AArch64/AArch64.td#L1127)). Once the minimum required LLVM version is updated to 13 we can use `apple-m1` here.