Fix a error suggestion for E0121 when using placeholder _ as return types on function signature.

Recommit after refactoring based on comment:
https://github.com/rust-lang/rust/pull/126017#issuecomment-2189149361

But when changing return type's lifetime to `ReError` will affect the subsequent borrow check process and cause test11 in typeck_type_placeholder_item.rs to lost E0515 message.
```rust
fn test11(x: &usize) -> &_ {
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
    &x //~ ERROR cannot return reference to function parameter(this E0515 msg will disappear)
}

```

0 files changed, 0 insertions, 0 deletions