Forgot to initialize JIT memory use fields.

bug:23128949

(cherry picked from commit b0d220835f2ddc03510f17fcc4fb4c64b426a0f5)

Change-Id: Iea81925ebd0fd60fe58a972269313a98f93fdac5
diff --git a/runtime/jit/jit_code_cache.cc b/runtime/jit/jit_code_cache.cc
index a0a70f8..94dbecb 100644
--- a/runtime/jit/jit_code_cache.cc
+++ b/runtime/jit/jit_code_cache.cc
@@ -126,6 +126,8 @@
       has_done_one_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),
       number_of_osr_compilations_(0) {