HASH_UPDATE always succeeds.

Fill in some missing "and returns 1" documentation. Really they all do but some
of _Final functions have codepaths to guard against user error.

Change-Id: I16e12ec20ab59e3ba6deaa4cfd67574ed0a56652
Reviewed-on: https://boringssl-review.googlesource.com/1901
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/include/openssl/sha.h b/include/openssl/sha.h
index bc10d38..9e71ec4 100644
--- a/include/openssl/sha.h
+++ b/include/openssl/sha.h
@@ -116,7 +116,7 @@
 /* SHA224_Init initialises |sha| and returns 1. */
 OPENSSL_EXPORT int SHA224_Init(SHA256_CTX *sha);
 
-/* SHA224_Update adds |len| bytes from |data| to |sha|. */
+/* 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
@@ -140,7 +140,7 @@
 /* SHA256_Init initialises |sha| and returns 1. */
 OPENSSL_EXPORT int SHA256_Init(SHA256_CTX *sha);
 
-/* SHA256_Update adds |len| bytes from |data| to |sha|. */
+/* 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
@@ -175,7 +175,7 @@
 /* SHA384_Init initialises |sha| and returns 1. */
 OPENSSL_EXPORT int SHA384_Init(SHA512_CTX *sha);
 
-/* SHA384_Update adds |len| bytes from |data| to |sha|. */
+/* 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
@@ -203,7 +203,7 @@
 /* SHA512_Init initialises |sha| and returns 1. */
 OPENSSL_EXPORT int SHA512_Init(SHA512_CTX *sha);
 
-/* SHA512_Update adds |len| bytes from |data| to |sha|. */
+/* 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