Omit OatMethodOffsets for classes without compiled code

Change-Id: If0d290f4aebc778ff12d8fed017c270ad2ac3220
diff --git a/runtime/exception_test.cc b/runtime/exception_test.cc
index 2e6b0a8..a5f9997 100644
--- a/runtime/exception_test.cc
+++ b/runtime/exception_test.cc
@@ -146,7 +146,7 @@
   ScopedObjectAccess soa(env);
 
   std::vector<uintptr_t> fake_stack;
-  ASSERT_EQ(kStackAlignment, 16);
+  ASSERT_EQ(kStackAlignment, 16U);
   ASSERT_EQ(sizeof(uintptr_t), sizeof(uint32_t));
 
 #if !defined(ART_USE_PORTABLE_COMPILER)