Prepare for a forthcoming new algorithm id.

* include/cipher.h (PUBKEY_ALGO_ECC): New.
* g10/keyid.c (pubkey_letter): Add letter 'C'.
--

ID 22 will be used for generic ECC, i.e. one which can be used for
ECDSA and ECDH.  The only support in 1.4 will pretty printing the
algorithm id.

g10/keyid.c

@@ -53,6 +53,7 @@ pubkey_letter( int algo )
       case PUBKEY_ALGO_DSA:	return 'D' ;
       case PUBKEY_ALGO_ECDSA:	return 'E' ;	/* ECC DSA (sign only)   */
       case PUBKEY_ALGO_ECDH:	return 'e' ;	/* ECC DH (encrypt only) */
+      case PUBKEY_ALGO_ECC:	return 'C' ;	/* ECC generic */
       default: return '?';
     }
 }