Re: BUG #15789: libpq compilation with OpenSSL 1.1.1b fails on Windows with Visual Studio 2017

On Wed, Jun 26, 2019 at 10:48:03AM +0900, Michael Paquier wrote:
> I am planning to back-patch the thing down to 9.4 where OpenSSL 1.1.0
> is supported, but first let's see if the buildfarm has anything to
> say.  I don't expect any issues as we basically don't change the logic
> build for 1.0.2, but nobody is never careful enough with this stuff.

The buildfarm did not complain, so I have backpatched the thing down
to 9.4.  There were some conflicts, mainly:
- On 9.4, we need to use USE_SSL to enable SSL in the builds.
- In ~9.6, we also need to set HAVE_RAND_OPENSSL for RAND_OpenSSL()
which is a function used by pgcrypto available in OpenSSL 1.1.0 and
newer.  This was removed in v10 as of fe0a0b59, so we can clean up a
bit things here.
--
Michael