Since return is inconsistent, I removed unnecessary parentheses and

unified them.
- return (0); -> return 0;
- return (1); -> return 1;
- return (-1); -> return -1;

Reviewed-by: Stephen Henson <steve@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4500)