Constify.
(cherry picked from commit 1abfa78a8ba714f7e47bd674db53dbe303cd1ce7)

doc/crypto/EVP_DigestVerifyInit.pod

diff --git a/doc/crypto/EVP_DigestVerifyInit.pod b/doc/crypto/EVP_DigestVerifyInit.pod
index f224488..c59866c 100644
--- a/doc/crypto/EVP_DigestVerifyInit.pod
+++ b/doc/crypto/EVP_DigestVerifyInit.pod
@@ -11,7 +11,7 @@
  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_DigestVerifyFinal(EVP_MD_CTX *ctx, unsigned char *sig, size_t siglen);
+ int EVP_DigestVerifyFinal(EVP_MD_CTX *ctx, const unsigned char *sig, size_t siglen);
 
 =head1 DESCRIPTION