`missing_inline_in_public_items` warns about `#[derive]`-generated code

[jonas-schievink]

Example:

#![warn(clippy::missing_inline_in_public_items)]

#[derive(Debug)]
pub struct S {}

warning: missing `#[inline]` for a method
 --> src/lib.rs:3:10
  |
3 | #[derive(Debug)]
  |          ^^^^^

I don't think Clippy should warn about this, since the user cannot control the code in question.

[llogiq]

This lint just needs a macro check.