(md4_init): Use memcpy for initializing the state vector.

(md4_update): Use MD_UPDATE.
(md4_digest): Inline md4_final processing, using MD_PAD. Use
_nettle_write_le32.
(md4_block): Renamed, to...
(md4_compress): ... new name. Take ctx pinter as argument.
(md4_final): Deleted function.

Rev: nettle/md4.c:1.2