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/imtable.h b/runtime/imtable.h
index 3c52fb8..48a8643 100644
--- a/runtime/imtable.h
+++ b/runtime/imtable.h
@@ -23,8 +23,8 @@
 
 #include "base/casts.h"
 #include "base/enums.h"
+#include "base/locks.h"
 #include "base/macros.h"
-#include "base/mutex.h"
 
 namespace art {