ratchet down the recursion limit because, at least in my testing,

under some configurations this still causes a stack overflow and
hence a crash

Author: nikomatsakis

src/test/compile-fail/issue-22638.rs

@@ -10,6 +10,8 @@
 
 #![allow(unused)]
 
+#![recursion_limit = "32"]
+
 #[derive(Clone)]
 struct A (B);