Changes to compile with gcc 4.6

Change-Id: I55908b3b98b49373ce948fd1f12e0a5cd56ae4f7
diff --git a/src/exception_test.cc b/src/exception_test.cc
index 559636f..eca1fa8 100644
--- a/src/exception_test.cc
+++ b/src/exception_test.cc
@@ -118,7 +118,7 @@
   fake_stack.push_back(0xEBAD6070);  // return pc
 
   // Pull Method* of NULL to terminate the trace
-  fake_stack.push_back(NULL);
+  fake_stack.push_back(0);
 
   // Set up thread to appear as if we called out of method_g_ at pc 3
   Thread* thread = Thread::Current();