Remove rustc-workspace-hack

Author: topecongiro

rustfmt-core/rustfmt-bin/Cargo.toml

@@ -45,8 +45,3 @@ rustfmt_lib = { path = "../rustfmt-lib", version = "1.0" }
 
 [dev-dependencies]
 lazy_static = "1.0"
-
-# A noop dependency that changes in the Rust repository, it's a bit of a hack.
-# See the `src/tools/rustc-workspace-hack/README.md` file in `rust-lang/rust`
-# for more information.
-rustc-workspace-hack = "1.0.0"