Add a --subkey switch to kernel signing utility.

src/platform/vboot_reference/utility/include/kernel_utility.h

 // Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef VBOOT_REFERENCE_KERNEL_UTILITY_H_
 #define VBOOT_REFERENCE_KERNEL_UTILITY_H_
 
 #include <string>
 
 extern "C" {
@@ skipping 59 matching lines @@
   int kernel_version_;
   int padding_;
   uint64_t kernel_len_;
   uint8_t* kernel_config_;
 
   std::string in_file_;
   std::string out_file_;
   bool is_generate_;  // Are we generating a new image?
   bool is_verify_;  // Are we just verifying an already signed image?
   bool is_describe_;  // Should we print out description of the image?
-  bool is_only_vblock_;  // Show we just output the verification block?
+  bool is_only_vblock_;  // Should we just output the verification block?
+  bool is_subkey_out_;  // Should we just output the subkey header?
 };
 
 }  // namespace vboot_reference
 
 #endif  // VBOOT_REFERENCE_FIRMWARE_UTILITY_H_