Remove thread refcount and remove NaClAppDtor()

src/native_client/src/trusted/service_runtime/nacl_app_thread.h

Index: src/native_client/src/trusted/service_runtime/nacl_app_thread.h
diff --git a/src/native_client/src/trusted/service_runtime/nacl_app_thread.h b/src/native_client/src/trusted/service_runtime/nacl_app_thread.h
index 2687ee3c5d6fa3eb986e04fd3f282e1062bcbe63..77c456beb316ca543c62e2e830ca9a60dc677eb3 100644
--- a/src/native_client/src/trusted/service_runtime/nacl_app_thread.h
+++ b/src/native_client/src/trusted/service_runtime/nacl_app_thread.h
@@ -40,8 +40,6 @@ struct NaClAppThread {
 
   int                       is_privileged;  /* can make "special" syscalls? */
 
-  uint32_t                  refcount;
-
   struct NaClClosureResult  result;
 
   uint32_t                  sysret;
@@ -159,10 +157,6 @@ int NaClAppThreadAllocSegCtor(struct NaClAppThread  *natp,
                               uintptr_t             sys_tdb_base,
                               size_t                tdb_size) NACL_WUR;
 
-int NaClAppThreadIncRef(struct NaClAppThread *natp);
-
-int NaClAppThreadDecRef(struct NaClAppThread *natp);
-
 EXTERN_C_END
 
 #endif  /* NATIVE_CLIENT_SERVICE_RUNTIME_NACL_APP_THREAD_H__ */