Deleted comments in type aliases

Some inline comments in type alias declarations are removed during formatting.

Steps to reproduce:

```console
$ rustfmt --version
rustfmt 1.4.38-stable (9d1b210 2022-02-23)
$ rustfmt --emit stdout <(echo 'type Cycle = [u64 /* seconds */; 3];')
```

Expected output:

```rust
type Cycle = [u64 /* seconds */; 3];
```

Actual output:

```rust
type Cycle = [u64; 3];
```