Make valgrind happier and stop us leaking so much we can can't run the tests on a device.

Change-Id: Id8f45dde788fd84c10b0b5807b2d12eae529ba5e
diff --git a/src/object.h b/src/object.h
index f3cd0fd..2657872 100644
--- a/src/object.h
+++ b/src/object.h
@@ -1276,7 +1276,7 @@
 
   // array of interfaces this class implements directly
   ObjectArray<Class>* interfaces_;
-  uint32_t* interfaces_type_idx_;
+  IntArray* interfaces_type_idx_;
 
   // static, private, and <init> methods
   ObjectArray<Method>* direct_methods_;