4025e95113
Make Hash{Set,Map}::with_hasher unstably const
Makes [`HashMap::with_hasher`](https://doc.rust-lang.org/stable/std/collections/hash_map/struct.HashMap.html#method.with_hasher) and [`HashSet::with_hasher`](https://doc.rust-lang.org/stable/std/collections/hash_set/struct.HashSet.html#method.with_hasher) `const`.
This allows
```rust
static GlobalState: Mutex<HashMap<i32, i32, SomeHasher>> = Mutex::new(HashMap::with_hasher(SomeHasher::new()))
```
Tracking issue: #102575