Support 64-bit volatiles and reference/pointer volatiles.

Change-Id: I62c0751747767c02d6c57afd0fce3db6c8b02510
diff --git a/src/mutex.cc b/src/mutex.cc
index 4dba6b7..f9e471b 100644
--- a/src/mutex.cc
+++ b/src/mutex.cc
@@ -18,6 +18,7 @@
 
 #include <errno.h>
 
+#include "heap.h" // for VERIFY_OBJECT_ENABLED
 #include "logging.h"
 #include "utils.h"