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_transmute/Cargo.toml

@@ -3,10 +3,8 @@ name = "rustc_transmute"
 version = "0.0.0"
 edition = "2021"
 
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
-
 [dependencies]
-tracing = "0.1"
+# tidy-alphabetical-start
 rustc_data_structures = { path = "../rustc_data_structures"}
 rustc_hir = { path = "../rustc_hir", optional = true}
 rustc_infer = { path = "../rustc_infer", optional = true}
@@ -14,16 +12,20 @@ rustc_macros = { path = "../rustc_macros", optional = true}
 rustc_middle = { path = "../rustc_middle", optional = true}
 rustc_span = { path = "../rustc_span", optional = true}
 rustc_target = { path = "../rustc_target", optional = true}
+tracing = "0.1"
+# tidy-alphabetical-end
 
 [features]
 rustc = [
-    "rustc_middle",
     "rustc_hir",
     "rustc_infer",
     "rustc_macros",
+    "rustc_middle",
     "rustc_span",
     "rustc_target",
 ]
 
 [dev-dependencies]
-itertools = "0.10.1"
+# tidy-alphabetical-start
+itertools = "0.10.1"
+# tidy-alphabetical-end