add 'L' after _OPENSSL_VERSION_PRE_RELEASE literals, fixes #8021

Reviewed-by: Kurt Roeckx <kurt@roeckx.be>
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/8036)