Refactor code from test/ to utils/ since they are not just used by tests.

src/platform/vboot_reference/utils/signature_digest.c

 /* 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.
  *
  * Utility that outputs the message digest of the contents of a file in a
  * format that can be used as input to OpenSSL for an RSA signature.
  * Needed until the stable OpenSSL release supports SHA-256/512 digests for
  * RSA signatures.
  * Outputs DigestInfo || Digest where DigestInfo is the OID depending on the
  * choice of the hash algorithm (see padding.c).
@@ skipping 48 matching lines @@
   write(1, info_digest, hash_size_map[algorithm] +
         digestinfo_size_map[algorithm]);
 
 failure:
   free(digest);
   free(info_digest);
   free(signature);
 
   return 0;
 }