Use tidy to sort crate attributes for all compiler crates.

We already do this for a number of crates, e.g. `rustc_middle`,
`rustc_span`, `rustc_metadata`, `rustc_span`, `rustc_errors`.

For the ones we don't, in many cases the attributes are a mess.
- There is no consistency about order of attribute kinds (e.g.
  `allow`/`deny`/`feature`).
- Within attribute kind groups (e.g. the `feature` attributes),
  sometimes the order is alphabetical, and sometimes there is no
  particular order.
- Sometimes the attributes of a particular kind aren't even grouped
  all together, e.g. there might be a `feature`, then an `allow`, then
  another `feature`.

This commit extends the existing sorting to all compiler crates,
increasing consistency. If any new attribute line is added there is now
only one place it can go -- no need for arbitrary decisions.

Exceptions:
- `rustc_log`, `rustc_next_trait_solver` and `rustc_type_ir_macros`,
  because they have no crate attributes.
- `rustc_codegen_gcc`, because it's quasi-external to rustc (e.g. it's
  ignored in `rustfmt.toml`).

compiler/rustc_mir_transform/src/lib.rs

@@ -1,8 +1,10 @@
+// tidy-alphabetical-start
 #![feature(assert_matches)]
 #![feature(box_patterns)]
 #![feature(const_type_name)]
 #![feature(cow_is_borrowed)]
 #![feature(decl_macro)]
+#![feature(if_let_guard)]
 #![feature(impl_trait_in_assoc_type)]
 #![feature(is_sorted)]
 #![feature(let_chains)]
@@ -12,7 +14,7 @@
 #![feature(round_char_boundary)]
 #![feature(try_blocks)]
 #![feature(yeet_expr)]
-#![feature(if_let_guard)]
+// tidy-alphabetical-end
 
 #[macro_use]
 extern crate tracing;