Rollup merge of #117420 - Jules-Bertholet:internal-unstable-stmt-expr…

…-attributes, r=petrochenkov

Make `#![allow_internal_unstable(..)]` work with `stmt_expr_attributes`

This is a necessary first step to fixing #117304, as explained in rust-lang/rust#117304 (comment).

`@rustbot` label T-compiler