whitelist_recursively sees through blacklisted types

Input C/C++ Header

typedef struct file_s {
} file_t;
void take_file(file_t* f);

Bindgen Invocation

    let bindings = bindgen::builder()
        .header_contents("test.h", ...)
        .trust_clang_mangling(false)
        .derive_copy(true)
        .blacklist_type("file_t")
        .whitelist_function("take_file")
        .layout_tests(false)
        .generate()
        .expect("bindgen error");

Actual Results

/* automatically generated by rust-bindgen */

#[repr(C)]
#[derive(Debug, Copy, Clone)]
pub struct file_s {}
extern "C" {
    pub fn take_file(f: *mut file_t);
}

Expected Results

Since no whitelisted items depend on file_s, I expect it to not be emitted:

/* automatically generated by rust-bindgen */

extern "C" {
    pub fn take_file(f: *mut file_t);
}

Start by reproducing the issue with the provided C++ header and bindgen invocation, then trace whitelist_recursively to see why the blacklisted file_t exposes file_s. Done means the generated bindings match the expected output and do not emit file_s; add or run a regression test for this case if the existing test layout supports it.