Fix typo in comment

The peek result is now called 'err', not just 'e'.
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4362)

apps/pkey.c

@@ -169,7 +169,7 @@ int pkey_main(int argc, char **argv)
             while ((err = ERR_peek_error()) != 0) {
                 BIO_printf(out, "Detailed error: %s\n",
                            ERR_reason_error_string(err));
-                ERR_get_error(); /* remove e from error stack */
+                ERR_get_error(); /* remove err from error stack */
             }
         }
         EVP_PKEY_CTX_free(ctx);