SHA256: Remove typedef for sha_transform_fn

#define SHA256_HEX_SIZE		65

#define SHA256_BLOCK_SIZE 	64

typedef uint sha_transform_fn (void *c, const byte *blks, size_t nblks);

struct sha256_context {

  u32  h0,h1,h2,h3,h4,h5,h6,h7;

  byte buf[128];			/* 128 is for SHA384 and SHA512 support, otherwise for SHA224 and SHA256 is 64 enough */

  u32 nblocks_high;

  int count;

  u32 blocksize;

  sha_transform_fn *transform;

  uint (*transform)(void *c, const byte *blks, size_t nblks);

};

#define sha224_context sha256_context	/* aliasing 'struct sha224_context' to 'struct sha256_context' */