Add tests for vboot_reference stateful_util.c

BUG=chromium-os:17564
TEST=make && make runtests

Change-Id: I5d55be2dfead0c5d7af72841cbd6c65485685cd6
Reviewed-on: http://gerrit.chromium.org/gerrit/6596
Reviewed-by: Stefan Reinauer <reinauer@chromium.org>
Tested-by: Randall Spangler <rspangler@chromium.org>
diff --git a/tests/utility_tests.c b/tests/utility_tests.c
index b8a1da9..9fc1dab 100644
--- a/tests/utility_tests.c
+++ b/tests/utility_tests.c
@@ -26,7 +26,7 @@
 
   /* Simple fill */
   memset(want, 123, 5);
-  TEST_EQ(0, dest - (char*)Memset(dest, 123, 5), "Memset() returns dest");
+  TEST_PTR_EQ(dest, Memset(dest, 123, 5), "Memset() returns dest");
   TEST_EQ(0, memcmp(dest, want, 128), "Memset()");
 
   /* Filling length 0 does nothing */