### What it does
Checks for attributes that allow lints without a reason.

(This requires the `lint_reasons` feature)

### Why is this bad?
Allowing a lint should always have a reason. This reason should be documented to
ensure that others understand the reasoning

### Example
```
#![feature(lint_reasons)]

#![allow(clippy::some_lint)]
```

Use instead:
```
#![feature(lint_reasons)]

#![allow(clippy::some_lint, reason = "False positive rust-lang/rust-clippy#1002020")]
```