CCM Authentication optimization

CCM   is now optimized. Instead of being computed twice,
libtomcrypt code has been optimized so that classical ccm_init, ccm_process,...
can be used incrementally (when the whole stream is not available when
starting the authentication).
CCM way of proceeding is now very closed to GCM authentication.
The checks at lines 105-108 for tag_len above is overlapping with what's done in ccm_init(). The tests in ccm_init() seems a bit more relaxed, but maybe it's good enough for compliance.