[nginx] SSL: fixed build with LibreSSL 2.8.0 (ticket #1605).

[Maxim Dounin]

details:   https://hg.nginx.org/nginx/rev/2cf1d945bbb3
branches:  stable-1.14
changeset: 7415:2cf1d945bbb3
user:      Maxim Dounin <mdounin at mdounin.ru>
date:      Fri Aug 10 20:49:06 2018 +0300
description:
SSL: fixed build with LibreSSL 2.8.0 (ticket #1605).

LibreSSL 2.8.0 "added const annotations to many existing APIs from OpenSSL,
making interoperability easier for downstream applications".  This includes
the const change in the SSL_CTX_sess_set_get_cb() callback function (see
9dd43f4ef67e), which breaks compilation.

To fix this, added a condition on how we redefine OPENSSL_VERSION_NUMBER
when working with LibreSSL (see 382fc7069e3a).  With LibreSSL 2.8.0,
we now set OPENSSL_VERSION_NUMBER to 0x1010000fL (OpenSSL 1.1.0), so the
appropriate conditions in the code will use "const" as it happens with
OpenSSL 1.1.0 and later versions.

diffstat:

 src/event/ngx_event_openssl.h |  4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diffs (16 lines):

diff --git a/src/event/ngx_event_openssl.h b/src/event/ngx_event_openssl.h
--- a/src/event/ngx_event_openssl.h
+++ b/src/event/ngx_event_openssl.h
@@ -36,8 +36,12 @@
 
 #if (defined LIBRESSL_VERSION_NUMBER && OPENSSL_VERSION_NUMBER == 0x20000000L)
 #undef OPENSSL_VERSION_NUMBER
+#if (LIBRESSL_VERSION_NUMBER >= 0x2080000fL)
+#define OPENSSL_VERSION_NUMBER  0x1010000fL
+#else
 #define OPENSSL_VERSION_NUMBER  0x1000107fL
 #endif
+#endif
 
 
 #if (OPENSSL_VERSION_NUMBER >= 0x10100001L)