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_target/Cargo.toml

@@ -4,19 +4,23 @@ version = "0.0.0"
 edition = "2021"
 
 [dependencies]
+# tidy-alphabetical-start
 bitflags = "1.2.1"
-tracing = "0.1"
-serde_json = "1.0.59"
-rustc_fs_util = { path = "../rustc_fs_util" }
 rustc_abi = { path = "../rustc_abi" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_feature = { path = "../rustc_feature" }
+rustc_fs_util = { path = "../rustc_fs_util" }
+rustc_index = { path = "../rustc_index" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_span = { path = "../rustc_span" }
-rustc_index = { path = "../rustc_index" }
+serde_json = "1.0.59"
+tracing = "0.1"
+# tidy-alphabetical-end
 
 [dependencies.object]
-version = "0.32.0"
+# tidy-alphabetical-start
 default-features = false
 features = ["elf", "macho"]
+version = "0.32.0"
+# tidy-alphabetical-end