Implement `Clone` for `Builder`

This is done by moving all the remaining `Builder` state into
`BindgenOptions` so any internal logic that affects `Builder` state only
runs once the builder is consumed by `Builder::generate`:

- move `input_headers` to `BindgenOptions`.
- move `input_header_contents` to `BindgenOptions`.
- derive `Clone` for `Builder`.

1 files changed, 1 insertions, 5 deletions

diff --git a/bindgen/ir/context.rs b/bindgen/ir/context.rs
index e2a13b8d..ba2db112 100644
--- a/bindgen/ir/context.rs
+++ b/bindgen/ir/context.rs
@@ -541,11 +541,7 @@ If you encounter an error missing from this list, please file an issue or a PR!"
         let root_module_id = root_module.id().as_module_id_unchecked();
 
         // depfiles need to include the explicitly listed headers too
-        let mut deps = BTreeSet::default();
-        if let Some(filename) = &options.input_header {
-            deps.insert(filename.clone());
-        }
-        deps.extend(options.extra_input_headers.iter().cloned());
+        let deps = options.input_headers.iter().cloned().collect();
 
         BindgenContext {
             items: vec![Some(root_module)],