…box, r=estebank

Specialize infinite-type "insert some indirection" suggestion for Option

Suggest `Option<Box<_>>` instead of `Box<Option<_>>` for infinitely-recursive members of a struct.

Not sure if I can get the span of the generic subty of the Option so I can make this a `+++`-style suggestion. The current output is a tiny bit less fancy looking than the original suggestion.

Should I limit the specialization to just `Option<Box<TheOuterStruct>>`? Because right now it applies to all `Option` members in the struct that are returned by `Representability::SelfRecursive`.

Fixes rust-lang#91402

r? `@estebank`
(since you wrote the original suggestion and are definitely most familiar with it!)

…zed, r=Dylan-DPC

Update target_has_atomic documentation for stabilization

`cfg(target_has_atomic)` was stabilized in rust-lang#93824, but this small note in the docs was not updated at the time.

small rustc_borrowck cleanup

r? `@jackh726` because of the second commit, seems like that comment was missed in rust-lang#91243

Fix typos in core::ptr docs

remove unused field from `infcx`

r? `@oli-obk` did we stop needing that for opaque types?