ART: Move to using locks.h instead of mutex.h

When only annotating lock requirements, use locks.h.

Bug: 119869270
Test: mmma art
Change-Id: I1608b03254712feff0072ebad012c3af0cc3dda4
diff --git a/runtime/stack.h b/runtime/stack.h
index 9d30115..0edf4f5 100644
--- a/runtime/stack.h
+++ b/runtime/stack.h
@@ -20,8 +20,8 @@
 #include <stdint.h>
 #include <string>
 
+#include "base/locks.h"
 #include "base/macros.h"
-#include "base/mutex.h"
 #include "quick/quick_method_frame_info.h"
 #include "stack_map.h"