test: Prevent run-fail/too-much-recursion from being optimized to nothing

Author: brson

src/test/run-fail/too-much-recursion.rs

@@ -3,5 +3,6 @@
 // Test that the task fails after hiting the recursion limit
 
 fn main() {
+    log(debug, "don't optimize me out");
     main();
 }