Replace every Vec in Target(Options) with it's Cow equivalent

compiler/rustc_target/src/spec/haiku_base.rs

@@ -1,11 +1,13 @@
 use crate::spec::{RelroLevel, TargetOptions};
 
+use super::cvs;
+
 pub fn opts() -> TargetOptions {
     TargetOptions {
         os: "haiku".into(),
         dynamic_linking: true,
         executables: true,
-        families: vec!["unix".into()],
+        families: cvs!["unix"],
         relro_level: RelroLevel::Full,
         ..Default::default()
     }