Rollup merge of #101031 - rust-lang:remove-unused-build-dep, r=bjorn3

Remove unused build dependency

There is no more `build.rs` so this dependency is unused.

r? `@Dylan-DPC`

Author: GuillaumeGomez

Cargo.lock

@@ -1280,7 +1280,6 @@ name = "error_index_generator"
 version = "0.0.0"
 dependencies = [
  "rustdoc",
- "walkdir",
 ]
 
 [[package]]

src/tools/error_index_generator/Cargo.toml

@@ -6,9 +6,6 @@ edition = "2021"
 [dependencies]
 rustdoc = { path = "../../librustdoc" }
 
-[build-dependencies]
-walkdir = "2"
-
 [[bin]]
 name = "error_index_generator"
 path = "main.rs"