Fix broken benchmarks

Cargo.toml

@@ -22,7 +22,7 @@ name = "secp256k1"
 path = "src/lib.rs"
 
 [features]
-unstable = []
+unstable = ["recovery", "rand-std"]
 default = ["std"]
 std = ["secp256k1-sys/std"]
 rand-std = ["rand/std"]

src/ecdh.rs

@@ -304,7 +304,6 @@ mod benches {
         let s = Secp256k1::signing_only();
         let (sk, pk) = s.generate_keypair(&mut thread_rng());
 
-        let s = Secp256k1::new();
         bh.iter( || {
             let res = SharedSecret::new(&pk, &sk);
             black_box(res);

src/recovery.rs

@@ -363,6 +363,10 @@ mod tests {
 
 #[cfg(all(test, feature = "unstable"))]
 mod benches {
+    use rand::{thread_rng, RngCore};
+    use test::{Bencher, black_box};
+    use super::{Message, Secp256k1};
+
     #[bench]
     pub fn bench_recover(bh: &mut Bencher) {
         let s = Secp256k1::new();