XFAIL two tests for stage0

Author: catamorphism

src/test/compile-fail/forgot-ret.rs

@@ -1,5 +1,5 @@
 // -*- rust -*-
-
+// xfail-stage0
 // error-pattern: not all control paths return
 
 fn god_exists(int a) -> bool {

src/test/run-fail/trivial-message2.rs

@@ -1,3 +1,4 @@
+// xfail-stage0
 /*
   This program should hang on the r <- po line.
  */