Add support for RSA-PSS to X509_certificate_type()

Reviewed-by: NPaul Dale <paul.dale@oracle.com>
Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6430)

crypto/x509/x509type.c

@@ -35,6 +35,9 @@ int X509_certificate_type(const X509 *x, const EVP_PKEY *pkey)
 /*              if (!sign only extension) */
         ret |= EVP_PKT_ENC;
         break;
+    case EVP_PKEY_RSA_PSS:
+        ret = EVP_PK_RSA | EVP_PKT_SIGN;
+        break;
     case EVP_PKEY_DSA:
         ret = EVP_PK_DSA | EVP_PKT_SIGN;
         break;