crypto: account for OpenSSL 1.1.0 function signature change.

[davidben]

In OpenSSL 1.1.0, SSL_CTX_sess_set_get_cb's callback has a slightly
different function signature, see [1]. Account for that with an
OPENSSL_VERSION_NUMBER check. This gets a little closer to 1.1.0
compatibility.

[1] https://git.openssl.org/gitweb/?p=openssl.git;a=blob;f=include/openssl/ssl.h;h=41cb36e9438e1debf4f1abba47f2d8d273883ffa;hb=abd30777cc72029e8a44e4b67201cae8ed3d19c1#l618

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• commit message follows commit guidelines

Affected core subsystem(s)

crypto

[mscdex]

I think this is already taken into account in #8491.

[mscdex]

Also, I think @shigeki will be working on a PR for OpenSSL 1.1.1 when it gets released...

[shigeki]

We're also waiting for FIPS support of 1.1.x. They are now working on it as https://www.openssl.org/blog/blog/2017/07/25/fips/.
This patch is included in #8491 and to be included in the future upgrade. We will stay on OpenSSL-1.0.2 until the release of OpenSSL-1.1.1 or Node-v10 to meet EOLS of 1.0.2.

@davidben I guess you need this for binding Node with BoringSSL. Could you keep this as your floating patch until we upgrade? It is no harm but I just want to avoid any confusions of misunderstanding that Node supports OpenSSL-1.1.0.

[davidben]

#8491 is out of date and has some mistakes in it, since fixed on master by #9409 and #9347. Is that PR still the plan for 1.1.0 compatibility? I had assumed it was abandoned. Were you not planning on adding 1.1.0 compatibility sooner than that? Things like distro packages probably aren't using the vendored OpenSSL and would probably appreciate fixes.

(We are indeed looking at advertising 1.1.0 rather than 1.0.2 in BoringSSL, which would need this patch, though not the rest of #8491. But if the patch isn't useful to you, we can certainly carry it or find some workaround. I am also happy to try updating #8491 if you all would prefer something less piecemeal.)

[davidben]

Oh, I see you already have #11828 which updates it. Sorry, I'd missed that.

Anyway, I'll defer to you all, however you all would like to do this.

[davidben]

Closing in favor of more complete 1.1.0 PR later.