Reuse already defined macros

instead of duplicity the code.

CLA: trivial

Signed-off-by: Petr Vorel <petr.vorel@gmail.com>

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/8127)