ignore: add some 'allow(dead_code)' annotations

I don't usually like doing this and would prefer to just delete unused
code, but I don't have the context required to understand why this code
is unused. A refresh of this crate is on the (distant) horizon, so I'll
just leave these here for now to squash the warnings.

crates/ignore/src/dir.rs

@@ -34,11 +34,13 @@ use crate::{
 /// IgnoreMatch represents information about where a match came from when using
 /// the `Ignore` matcher.
 #[derive(Clone, Debug)]
+#[allow(dead_code)]
 pub(crate) struct IgnoreMatch<'a>(IgnoreMatchInner<'a>);
 
 /// IgnoreMatchInner describes precisely where the match information came from.
 /// This is private to allow expansion to more matchers in the future.
 #[derive(Clone, Debug)]
+#[allow(dead_code)]
 enum IgnoreMatchInner<'a> {
     Override(overrides::Glob<'a>),
     Gitignore(&'a gitignore::Glob),