When a type alias is locally re-exported from a private module (an implicit
inline), rustdoc drops its `cfg` attributes because it treats it like a
standard un-inlined re-export. Since type aliases have no inner fields to
carry the `cfg` badge (unlike structs or enums), the portability info
is lost entirely.
This patch explicitly preserves the target's `cfg` metadata when the
generated item is a `TypeAliasItem`, ensuring the portability badge
renders correctly without breaking standard cross-crate re-export behavior.
Shivendra Sharma