Missing initialization

Change-Id: Ib2a75f3fac032e19efb89119d5aabed1aed6b05a
diff --git a/src/runtime.cc b/src/runtime.cc
index 99dc0d8..31b6539 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -61,6 +61,7 @@
       java_vm_(NULL),
       jni_stub_array_(NULL),
       abstract_method_error_stub_array_(NULL),
+      system_class_loader_(NULL),
       shutting_down_(false),
       started_(false),
       vfprintf_(NULL),