doc aliases don't work on reexports

[GuillaumeGomez]

For example with this code:

#[doc(alias = "->a")]
pub use ::std as x;
#[doc(alias = "->b")]
pub struct Foo;

We can't search for ->a but we can search for ->b.

[GuillaumeGomez]

Actually the problem is even bigger: aliases reexports are not generated for the search index.