Compilation error with v0.10.2 and allow_multithreading feature

[jbangelo]

Description

There's a compilation error when building the latest release with the allow_multithreading feature enabled. The BinLayout::with_cpu_count function calls BinLayout::new which does not exist.

Reproduction Steps

Check out v0.10.2 and build with the allow_multithreading feature:

git checkout 0.10.2
cargo build --features allow_multithreading

And you should get the following error:

error[E0599]: no function or associated item named `new` found for struct `BinLayout<K>` in the current scope
  --> src/sort/parallel/bin_layout.rs:25:25
   |
25 |         Some(BinLayout::new(min_key, max_key, max_bins_count))
   |                         ^^^ function or associated item not found in `BinLayout<_>`
   |
  ::: src/sort/bin_layout.rs:9:1
   |
 9 | pub(crate) struct BinLayout<K> {
   | ------------------------------ function or associated item `new` not found for this struct
   |
note: if you're trying to build a new `BinLayout<_>` consider using one of the following associated functions:
      parallel::bin_layout::<impl BinLayout<K>>::with_cpu_count
      BinLayout::<K>::with_keys
  --> src/sort/parallel/bin_layout.rs:11:5
   |
11 | /     pub(super) fn with_cpu_count<T, F>(cpu: usize, slice: &[T], key: F) -> Option<Self>
12 | |     where
13 | |         T: Copy + Send + Sync,
14 | |         F: KeyFn<T, K> + Send + Sync,
   | |_____________________________________^
   |
  ::: src/sort/bin_layout.rs:71:5
   |
71 |       pub fn with_keys<T, F: KeyFn<T, K>>(array: &[T], key: F) -> Option<Self> {
   |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

For more information about this error, try `rustc --explain E0599`.

[NailxSharipov]

Thanks for the early report and PR.

I also added CI checks #6 to test both default and allow_multithreading