Fix the docs too

Reviewed-by: NStephen Henson <steve@openssl.org>
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1367)

doc/crypto/X509_get_subject_name.pod

@@ -11,10 +11,10 @@ subject names
 
  #include <openssl/x509.h>
 
- X509_NAME *X509_get_subject_name(X509 *x);
+ X509_NAME *X509_get_subject_name(const X509 *x);
  int X509_set_subject_name(X509 *x, X509_NAME *name);
 
- X509_NAME *X509_get_issuer_name(X509 *x);
+ X509_NAME *X509_get_issuer_name(const X509 *x);
  int X509_set_issuer_name(X509 *x, X509_NAME *name);
 
  X509_NAME *X509_REQ_get_subject_name(X509_REQ *req);

doc/crypto/X509_get_version.pod

@@ -10,7 +10,7 @@ certificate request or CRL version
 
  #include <openssl/x509.h>
 
- long X509_get_version(X509 *x);
+ long X509_get_version(const X509 *x);
  int X509_set_version(X509 *x, long version);
 
  long X509_REQ_get_version(X509_REQ *req);