Adds tests & bechmarks for the avx2 engine

Author: dequbed

Cargo.toml

@@ -15,6 +15,11 @@ edition = "2018"
 name = "benchmarks"
 harness = false
 
+[[bench]]
+name = "avx2benchmarks"
+harness = false
+required-features = ["avx2"]
+
 [dev-dependencies]
 criterion = "0.3.4"
 rand = "0.6.1"