[RFC PATCH 0/7] EAX transform

[Ian Jackson]

Here is another RFC series for review.  Here, I provide a new
transform using EAX, Serpent (and SHA512 to hash the DH key).

 1/7 serpent: const-correct
 2/7 crypto: Copy an AES (Rijndael) implementation into tree
 3/7 EAX: provide an implementation of EAX
 4/7 transform: split out transform-common.h
 5/7 transform: Allow DH to set the key size
 6/7 transform: Pass a direction flag to the transform
 7/7 transform: Provide Serpment-EAX transform

Most of these are quite uninteresting, but the final patch could do
with some proper review.

The SHA512 implementation comes from coreutils, so we inherit its
GPL3+ licence.