test: Add a test case for the "self" region in enums

src/test/run-pass/regions-self-in-enums.rs

@@ -0,0 +1,16 @@
+enum int_wrapper {
+    int_wrapper_ctor(&int)
+}
+
+fn main() {
+    unsafe {
+        let x = 3;
+        let y = int_wrapper_ctor(&x);
+        let z : ∫
+        alt y {
+            int_wrapper_ctor(zz) { z = zz; }
+        }
+        log(debug, *z);
+    }
+}
+