Fix bug where private item with intermediate doc hidden re-export was not inlined
This fixes this bug:
```rust
mod private {
/// Original.
pub struct Bar3;
}
/// Hidden.
#[doc(hidden)]
pub use crate::private::Bar3;
/// Visible.
pub use self::Bar3 as Reexport;
```
In this case, `private::Bar3` should be inlined and renamed `Reexport` but instead we have:
```
pub use self::Bar3 as Reexport;
```
and no links.
There were actually two issues: the first one is that we forgot to check if the next intermediate re-export was doc hidden. The second was that we made the `#[doc(hidden)]` attribute inheritable, which shouldn't be possible.
r? `@notriddle`
0d6749c2af