Fix signatures of EVP_Digest{Sign,Verify}Update

These are implemented as macros delegating to `EVP_DigestUpdate`, which
takes a `size_t` as its third argument, not an `unsigned int`.

CLA: trivial

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>

doc/crypto/EVP_DigestSignInit.pod

diff --git a/doc/crypto/EVP_DigestSignInit.pod b/doc/crypto/EVP_DigestSignInit.pod
index c97a732..13d6c7b 100644
--- a/doc/crypto/EVP_DigestSignInit.pod
+++ b/doc/crypto/EVP_DigestSignInit.pod
@@ -10,7 +10,7 @@
 
  int EVP_DigestSignInit(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx,
                         const EVP_MD *type, ENGINE *e, EVP_PKEY *pkey);
- int EVP_DigestSignUpdate(EVP_MD_CTX *ctx, const void *d, unsigned int cnt);
+ int EVP_DigestSignUpdate(EVP_MD_CTX *ctx, const void *d, size_t cnt);
  int EVP_DigestSignFinal(EVP_MD_CTX *ctx, unsigned char *sig, size_t *siglen);
 
 =head1 DESCRIPTION

doc/crypto/EVP_DigestVerifyInit.pod

diff --git a/doc/crypto/EVP_DigestVerifyInit.pod b/doc/crypto/EVP_DigestVerifyInit.pod
index 15db70e..c665d12 100644
--- a/doc/crypto/EVP_DigestVerifyInit.pod
+++ b/doc/crypto/EVP_DigestVerifyInit.pod
@@ -10,7 +10,7 @@
 
  int EVP_DigestVerifyInit(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx,
                         const EVP_MD *type, ENGINE *e, EVP_PKEY *pkey);
- int EVP_DigestVerifyUpdate(EVP_MD_CTX *ctx, const void *d, unsigned int cnt);
+ int EVP_DigestVerifyUpdate(EVP_MD_CTX *ctx, const void *d, size_t cnt);
  int EVP_DigestVerifyFinal(EVP_MD_CTX *ctx, const unsigned char *sig, size_t siglen);
 
 =head1 DESCRIPTION