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/class_loader_utils.h b/runtime/class_loader_utils.h
index 945d659..69476df 100644
--- a/runtime/class_loader_utils.h
+++ b/runtime/class_loader_utils.h
@@ -18,7 +18,7 @@
 #define ART_RUNTIME_CLASS_LOADER_UTILS_H_
 
 #include "art_field-inl.h"
-#include "base/mutex.h"
+#include "base/locks.h"
 #include "handle_scope.h"
 #include "jni/jni_internal.h"
 #include "mirror/class_loader.h"