Removed unused mojo_nacl code and GYP targets.

mojo/nacl/irt_entry_mojo.c

-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "mojo/nacl/mojo_irt.h"
-#include "native_client/src/public/irt_core.h"
-
-static size_t irt_query(const char* interface_ident,
-                        void* table, size_t tablesize) {
-  // TODO(teravest): Add query for the Mojo IRT interface, when introduced.
-  size_t rc = mojo_irt_query(interface_ident, table, tablesize);
-  if (rc != 0)
-    return rc;
-
-  return nacl_irt_query_core(interface_ident, table, tablesize);
-}
-
-void nacl_irt_start(uint32_t* info) {
-  nacl_irt_init(info);
-  nacl_irt_enter_user_code(info, irt_query);
-}