Forgot to initialize JIT memory use fields.

Change-Id: I82ae97adffd8e633de048f044cdbdb953b2f9763
diff --git a/runtime/jit/jit_code_cache.cc b/runtime/jit/jit_code_cache.cc
index 6348dda..478b164 100644
--- a/runtime/jit/jit_code_cache.cc
+++ b/runtime/jit/jit_code_cache.cc
@@ -126,6 +126,8 @@
       has_done_full_collection_(false),
       last_update_time_ns_(0),
       garbage_collect_code_(garbage_collect_code),
+      used_memory_for_data_(0),
+      used_memory_for_code_(0),
       number_of_compilations_(0) {
 
   DCHECK_GE(max_capacity, initial_code_capacity + initial_data_capacity);