XFAIL do-while-body-fails

Doesn't work w/out optimizations

Author: brson

Diff for: src/test/run-fail/do-while-body-fails.rs

@@ -1,3 +1,6 @@
+// xfail-stage1
+// xfail-stage2
+// xfail-stage3
 // error-pattern:quux
 fn main() {
     let x: int = do { fail "quux" } while (true);