Rollup merge of #47120 - clarcharr:io_error_debug, r=dtolnay

Better Debug impl for io::Error.

This PR includes the below changes:

1. The former impl wrapped the entire thing in `Error { repr: ... }` which was unhelpful; this has been removed.
2. The `Os` variant of `io::Error` included the code and message, but not the kind; this has been fixed.
3. The `Custom` variant of `io::Error` included a `Custom(Custom { ... })`, which is now just `Custom { ... }`.

Example of previous impl:

```rust
Error {
    repr: Custom(
        Custom {
            kind: InvalidData,
            error: Error {
                repr: Os {
                    code: 2,
                    message: "no such file or directory"
                }
            }
        }
    )
}
```

Example of new impl:

```rust
Custom {
    kind: InvalidData,
    error: Os {
        code: 2,
        kind: NotFound,
        message: "no such file or directory"
    }
}
```

0 files changed, 0 insertions, 0 deletions