refactor: clean up by using cfg-if where possible

Signed-off-by: Stephen Waits <steve@waits.net>

Cargo.toml

@@ -37,6 +37,7 @@ harness = false
 
 [dependencies]
 array-init = "2.1.0"
+cfg-if = "1.0.0"
 num-traits = "0.2.15"
 rand = "0.8.5"
 serde = {version = "1.0.152", features = ["serde_derive"]}