fix many configurations

src/lib.rs

@@ -67,3 +67,6 @@ pub(crate) unsafe fn heap_drop<T>(x: NonNull<T>) {
 pub(crate) unsafe fn heap_remove<T>(x: NonNull<T>) -> T {
     unsafe { *Box::from_raw(x.as_ptr()) }
 }
+
+/// This is a type only used by cbindgen to have a type for pointers.
+pub struct UdpSocket;