Revert md_len removal from SHA256_CTX and SHA512_CTX.

This reverts commits:
- 91586371422dae70481c39752e55f01f50e9a93a
- a90aa643024459c1698dbec84f4c79a3238b3db8
- c0d8b83b4462a0eb1889f32dbd7f46e83f4dbc81

It turns out code outside of BoringSSL also mismatches Init and Update/Final
functions. Since this is largely cosmetic, it's probably not worth the cost to
do this.

Change-Id: I14e7b299172939f69ced2114be45ccba1dbbb704
Reviewed-on: https://boringssl-review.googlesource.com/7793
Reviewed-by: Adam Langley <agl@google.com>

include/openssl/sha.h

diff --git a/include/openssl/sha.h b/include/openssl/sha.h
index 6e3df8f..48a52e8 100644
--- a/include/openssl/sha.h
+++ b/include/openssl/sha.h
@@ -128,15 +128,15 @@
 /* SHA224_DIGEST_LENGTH is the length of a SHA-224 digest. */
 #define SHA224_DIGEST_LENGTH 28
 
-/* SHA224_Init initialises |sha| and returns one. */
+/* SHA224_Init initialises |sha| and returns 1. */
 OPENSSL_EXPORT int SHA224_Init(SHA256_CTX *sha);
 
-/* SHA224_Update adds |len| bytes from |data| to |sha| and returns one. */
+/* SHA224_Update adds |len| bytes from |data| to |sha| and returns 1. */
 OPENSSL_EXPORT int SHA224_Update(SHA256_CTX *sha, const void *data, size_t len);
 
 /* SHA224_Final adds the final padding to |sha| and writes the resulting digest
  * to |md|, which must have at least |SHA224_DIGEST_LENGTH| bytes of space. It
- * returns one. */
+ * returns one on success and zero on programmer error. */
 OPENSSL_EXPORT int SHA224_Final(uint8_t *md, SHA256_CTX *sha);
 
 /* SHA224 writes the digest of |len| bytes from |data| to |out| and returns
@@ -153,15 +153,15 @@
 /* SHA256_DIGEST_LENGTH is the length of a SHA-256 digest. */
 #define SHA256_DIGEST_LENGTH 32
 
-/* SHA256_Init initialises |sha| and returns one. */
+/* SHA256_Init initialises |sha| and returns 1. */
 OPENSSL_EXPORT int SHA256_Init(SHA256_CTX *sha);
 
-/* SHA256_Update adds |len| bytes from |data| to |sha| and returns one. */
+/* SHA256_Update adds |len| bytes from |data| to |sha| and returns 1. */
 OPENSSL_EXPORT int SHA256_Update(SHA256_CTX *sha, const void *data, size_t len);
 
 /* SHA256_Final adds the final padding to |sha| and writes the resulting digest
  * to |md|, which must have at least |SHA256_DIGEST_LENGTH| bytes of space. It
- * returns one. */
+ * returns one on success and zero on programmer error. */
 OPENSSL_EXPORT int SHA256_Final(uint8_t *md, SHA256_CTX *sha);
 
 /* SHA256 writes the digest of |len| bytes from |data| to |out| and returns
@@ -177,7 +177,7 @@
   uint32_t h[8];
   uint32_t Nl, Nh;
   uint8_t data[SHA256_CBLOCK];
-  unsigned num;
+  unsigned num, md_len;
 };
 
 
@@ -189,15 +189,15 @@
 /* SHA384_DIGEST_LENGTH is the length of a SHA-384 digest. */
 #define SHA384_DIGEST_LENGTH 48
 
-/* SHA384_Init initialises |sha| and returns one. */
+/* SHA384_Init initialises |sha| and returns 1. */
 OPENSSL_EXPORT int SHA384_Init(SHA512_CTX *sha);
 
-/* SHA384_Update adds |len| bytes from |data| to |sha| and returns one. */
+/* SHA384_Update adds |len| bytes from |data| to |sha| and returns 1. */
 OPENSSL_EXPORT int SHA384_Update(SHA512_CTX *sha, const void *data, size_t len);
 
 /* SHA384_Final adds the final padding to |sha| and writes the resulting digest
  * to |md|, which must have at least |SHA384_DIGEST_LENGTH| bytes of space. It
- * returns one. */
+ * returns one on success and zero on programmer error. */
 OPENSSL_EXPORT int SHA384_Final(uint8_t *md, SHA512_CTX *sha);
 
 /* SHA384 writes the digest of |len| bytes from |data| to |out| and returns
@@ -218,15 +218,15 @@
 /* SHA512_DIGEST_LENGTH is the length of a SHA-512 digest. */
 #define SHA512_DIGEST_LENGTH 64
 
-/* SHA512_Init initialises |sha| and returns one. */
+/* SHA512_Init initialises |sha| and returns 1. */
 OPENSSL_EXPORT int SHA512_Init(SHA512_CTX *sha);
 
-/* SHA512_Update adds |len| bytes from |data| to |sha| and returns one. */
+/* SHA512_Update adds |len| bytes from |data| to |sha| and returns 1. */
 OPENSSL_EXPORT int SHA512_Update(SHA512_CTX *sha, const void *data, size_t len);
 
 /* SHA512_Final adds the final padding to |sha| and writes the resulting digest
  * to |md|, which must have at least |SHA512_DIGEST_LENGTH| bytes of space. It
- * returns one. */
+ * returns one on success and zero on programmer error. */
 OPENSSL_EXPORT int SHA512_Final(uint8_t *md, SHA512_CTX *sha);
 
 /* SHA512 writes the digest of |len| bytes from |data| to |out| and returns
@@ -245,7 +245,7 @@
     uint64_t d[16];
     uint8_t p[128];
   } u;
-  unsigned num;
+  unsigned num, md_len;
 };