Clean up rustc_*/Cargo.toml.

- Sort dependencies and features sections.
- Add `tidy` markers to the sorted sections so they stay sorted.
- Remove empty `[lib`] sections.
- Remove "See more keys..." comments.

Excluded files:
- rustc_codegen_{cranelift,gcc}, because they're external.
- rustc_lexer, because it has external use.
- stable_mir, because it has external use.

compiler/rustc_mir_build/Cargo.toml

@@ -3,25 +3,25 @@ name = "rustc_mir_build"
 version = "0.0.0"
 edition = "2021"
 
-[lib]
-
 [dependencies]
-rustc_arena = { path = "../rustc_arena" }
-tracing = "0.1"
+# tidy-alphabetical-start
 either = "1"
-rustc_middle = { path = "../rustc_middle" }
 rustc_apfloat = "0.2.0"
+rustc_arena = { path = "../rustc_arena" }
+rustc_ast = { path = "../rustc_ast" }
 rustc_data_structures = { path = "../rustc_data_structures" }
-rustc_index = { path = "../rustc_index" }
 rustc_errors = { path = "../rustc_errors" }
 rustc_fluent_macro = { path = "../rustc_fluent_macro" }
 rustc_hir = { path = "../rustc_hir" }
+rustc_index = { path = "../rustc_index" }
 rustc_infer = { path = "../rustc_infer" }
 rustc_macros = { path = "../rustc_macros" }
+rustc_middle = { path = "../rustc_middle" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
 rustc_trait_selection = { path = "../rustc_trait_selection" }
-rustc_ast = { path = "../rustc_ast" }
 smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
+tracing = "0.1"
+# tidy-alphabetical-end