rustdoc: Re-exported macros 2.0 are rendered as `macro_rules!`

[camelid]

I noticed this while working on a fix for #86208. I think the issue is just that clean/inline.rs does not check if the macro is a macro_rules!, whereas clean/mod.rs does.

core (original)

std (re-export)

[camelid]

Assigning myself because I'd like to look into this.