Mark DemangleOptions as repr(C) since it's used directly by the C api.

Author: khuey

src/lib.rs

@@ -85,6 +85,7 @@ use std::fmt;
 
 /// Options to control the demangling process.
 #[derive(Clone, Copy, Debug, Default)]
+#[repr(C)]
 pub struct DemangleOptions {
     no_params: bool,
     no_return_type: bool,