Remove unused files, and tidy the directory structure of the remaining ones.

host/lib/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.
  */
 
 #include "signature_digest.h"
 #define OPENSSL_NO_SHA
 #include <openssl/engine.h>
 #include <openssl/pem.h>
 #include <openssl/rsa.h>
@@ skipping 54 matching lines @@
                                   key,  /* Key to use. */
                                   RSA_PKCS1_PADDING))  /* Padding to use. */
       debug("SignatureBuf(): RSA_private_encrypt() failed.\n");
   }
   fclose(key_fp);
   if (key)
     RSA_free(key);
   Free(signature_digest);
   return signature;
 }