Make criterion a normal dev-dependency

Author: Amanieu

.github/workflows/ci.yml

@@ -13,4 +13,4 @@ jobs:
           components: rustfmt
       - run: cargo fmt -- --check
       - run: cargo test
-      - run: cargo bench --features criterion
+      - run: cargo bench

Cargo.toml

@@ -22,12 +22,9 @@ once_cell = "1.5.2"
 # this is required to gate `nightly` related code paths
 cfg-if = "1.0.0"
 
-# This is actually a dev-dependency, see https://github.com/rust-lang/cargo/issues/1596
-criterion = { version = "0.4.0", optional = true }
-
 [dev-dependencies]
+criterion = "0.4.0"
 
 [[bench]]
 name = "thread_local"
-required-features = ["criterion"]
 harness = false

benches/thread_local.rs

@@ -1,6 +1,3 @@
-extern crate criterion;
-extern crate thread_local;
-
 use criterion::{black_box, BatchSize};
 
 use thread_local::ThreadLocal;