Fix object verification.

Refactor VERIFY_OBJECT_ENABLED to become less brittle to change enum and global
constant.

Change-Id: Ie405106be81dce9a913730c7f46a5659582fa18b
diff --git a/src/base/mutex.cc b/src/base/mutex.cc
index 1975f3b..912e7fd 100644
--- a/src/base/mutex.cc
+++ b/src/base/mutex.cc
@@ -25,7 +25,7 @@
 #include "mutex-inl.h"
 #include "runtime.h"
 #include "scoped_thread_state_change.h"
-#include "thread.h"
+#include "thread-inl.h"
 #include "utils.h"
 
 namespace art {