Function gtk_sys::gtk_file_chooser_add_choice

pub unsafe extern "C" fn gtk_file_chooser_add_choice(
    chooser: *mut GtkFileChooser, 
    id: *const c_char, 
    label: *const c_char, 
    options: *mut *const c_char, 
    option_labels: *mut *const c_char
)

This is supported on crate feature v3_22 only.