[PATCH] SSL: let it build against LibreSSL

[Piotr Sikora]

Hey,
this change is based on BoringSSL change [1], but I can rebase it if
we decide that the #ifndefs are not wanted after all.

[1]  http://mailman.nginx.org/pipermail/nginx-devel/2014-July/005656.html

Best regards,
Piotr Sikora